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A TREATISE 



ON THE 



WESTINGHOUSE 



AIR BRAKE 



j/ PREPARED FOR STUDENTS OF 

The International Correspondence Schools 
scranton, pa. 



COPIOUSLY ILLUSTRATED WITH LINE DRAWINGS AND 

COLORED PLATES, AND CONTAINING A LARGE 

NUMBER OF PRACTICAL QUESTIONS 



FIRST EDITION 



scranton 

The Colliery Engineer Co. 

1900 

V. 



20784 

^ CO, . ,v EOi 






Library of Ccn 

Two Copies Recev^io 
JUL 16 1900 

Copyright atry 

M -mm copy. 

ORDER DIVISION 



65358 



Copyright, 1900, by The Colliery Engineer Company 



The Air Brake: Copyright, 1899, by The Colliery Engineer Company. 



Printed by 

The Colliery Engineer Company, 

scranton, penna. 




« 



f 



1* 



7769 



PREFACE. 



This volume contains the Instruction and Question Papers 
composing The Air Brake Course. 

The Papers on the Westinghouse Air Brake are very 
thorough and complete. These Papers not only give an 
exhaustive description of each piece of the air-brake appa- 
ratus, but they also deal with all its defects, their causes and 
remedies; operating and testing; calculation of the braking 
force; air-signaling system; and devices for controlling heavy 
trains on down grades. In short, these Papers contain every- 
thing relating to the subject that it is necessary for the 
practical man to know. No work treating the subject in 
such a thorough, comprehensive, and practical manner has 
heretofore been published. 

Special attention is called to the illustrations; whenever it has 
been thought that a cut would help make the subject clearer, it 
has been given, and considerable ingenuity has been displayed 
at times in arranging and presenting the various views and 
sections in such a manner as to enable those who are not 
accustomed to reading drawings to understand the sometimes 
complicated mechanisms and apparatus that are illustrated. 
To make still clearer the action of the Brake Apparatus in its 
various working positions, we have printed many of the larger 
cuts in colors — one color denoting main-reservoir pressure; 
another color, auxiliary-reservoir pressure; and so on, any one 
color always denoting the same kind of pressure. Similarly 
in the pump drawings, two colors are employed to represent 
live and exhaust steam, respectively, the former of these two 
being also used in the pump governor. Altogether eight colors 
are employed, and the reader is able to distinguish at a glance 
the nature of the pressure in each part of the apparatus at any 



iv PREFACE. 

particular position of the working parts. Nothing like these 
color plates has ever before been published in a work on 
The Air Brake. 

The method of numbering the pages, cuts, articles, etc. is 
such that each Paper and Part is complete in itself; hence, in 
order to make the indexes intelligible, it was necessary to give 
each Paper and Part a number. This number is placed at the 
top of each page, on the headline, opposite the page number; 
and, to distinguish it from the page number, it is preceded 
by the printer's section mark §. Consequently, a reference 
such as § 3, page 12, will be readily found by looking at the 
inside of the headlines until § 3 is found, and then through § 3 
until page 12 is found. 

The International Correspondence Schools. 



CONTENTS. 



Historical. Section. 

The Straight-Air Brake 

The Automatic Brake 

Westinghouse Automatic Brake. 

General Arrangement of Brake 

Main Reservoir 

Air Gauges , . 

Pump Governors 

The 8- Inch Air Pump 

The 9^-Inch Air Pump 

Plain Triple Valve 

Quick- Action Triple Valve 

Car Equipments 

Train-Pipe Couplings 

Retaining Valve 

D-8 Brake Valve 

F-6 Brake Valve 

Defects and Remedies in Brake System. 

Pump Governors 2 

Pumps 2 

Quick- Action Triple Valve 2 

Plain Triple Valve 2 

Care of Triples 2 

Freight Equipment 2 

Retaining Valve 2 

D-8 Brake Valve 2 

F-6 Brake Valve 2 

Care of Engineer's Valves 2 

Equalizing Reservoir ........ 2 



Page. 
1 
3 



10 
13 
16 
21 

27 
34 
40 
43 
45 
47 
54 

1 
4 
20 
29 
30 
31 
34 
37 
42 
46 
48 



vi CONTENTS. 

Operating and Testing. Section. Page. 

Make-Up of Train . . . 3 1 

Making Up Freight Trains ...... 3 4 

Testing Brakes 3 5 

Handling Trains 3 17 

Running 3 26 

Piston Travel and Its Adjustment .... 3 35 

Brake Gear. 

Levers and Leverage 3 44 

Brake Power 3 58 

Train Air-Signaling System. 

General Arrangement of Apparatus ... 4 1 

Description of Apparatus 4 4 

Signaling 4 11 

Defects in the Signaling System .... 4 11 

Terminal Test of Apparatus 4 15 

High-Speed Brake. 

High-Speed Service ' . . ' 4 17 

General Arrangement of Apparatus ... 4 18 

Operation of Apparatus 4 21 

Operating the Brake 4 28 

Control of Heavy Freight Trains on Grades. 

Westinghouse Special Apparatus .... 4 32 

Water Brake 4 36 

Sweeney Air Compressor 4 41 

Questions. Sections. 

The Air Brake, Parts 1 to 4 . ; . . , . . 1 to 4 



Red 




Main- Reservoir Pressure. 



Pink. 



Brake- Cylinder Pressure. 



Green. 




A uxiliary- Reservoir Pressure. 



Light Green. 




Brake- Valve- Reservoir Pressure. 

{Equalizing Reservoir.) 



Orange. 




Atmospheric Pressure. 



Yellow. 



Train- Pipe Pressure. 



Blue. 




Live Steam. 



Light Blue. 




Exhaust Steam. 



KEY TO THE COLOR PLATES. 



The Air Brake 

(PART 1.) 



HISTORICAL. 

1. The forms of brake in general use before the adoption of 
the air brake were the hand and the spring brake; most trains, 
however, were controlled by hand power. 

Both of these brakes were ineffective, even for the slower 
speed of trains in those days, and a field of invention was open 
for the production of a brake that would permit of a higher 
safe speed for trains. Mr. George Westinghouse, Jr., brought 
out the first form of air brake, called the "Straight-Air" 
Brake, in 1869. 

THE STRAIGHT-AIR BRAKE. 

2. General Equipment. — The engine equipment that 
was employed in connection with this kind of brake consisted 
of a pump, a main reservoir, an engineer's valve, a gauge, and 
a train line. A pipe connection between the pump and main 
reservoir allowed the pump to compress air directly into this 
reservoir, and the air thus compressed was stored in the reser- 
voir for braking purposes. A pipe led from the main reservoir 
to the engineer's valve, which at that time was a three-way 
cock. This valve had three positions, namely, lap, service, and 
release. The improved three-way cocks had a running position 
and an excess-pressure valve. 

With the valve on lap, all ports were closed, and there could 
be no passage of air through the valve; in service position, a port 

l\ 



THE AIR BRAKE. 



was opened between the main reservoir and the train line; and 
in release position, a port connection was established between the 
train line and the atmosphere. 

On each car, and on the tender, were placed a brake cylinder 
and a train pipe, a hose being provided at each end of the train 
pipe to enable the train line to be coupled up throughout the 
train. The train pipe on the car was directly connected with 
the brake cylinder, so that, if any pressure was in the train pipe, 
the same pressure was in the brake cylinder. 

3. Operation. — While the brakes were off, and before they 
could be operated, the pump compressed the desired pressure 
into the main reservoir. If the engineer wished to apply the 
brakes, he placed the three-way cock in service position. This 
position of the valve allowed main-reservoir air to pass through 
the three-way cock into the train line, and thence into the brake 
cylinders, since the brake cylinders were directly connected 
with the train line. When the desired pressure had been 
admitted to the train line and brake cylinders, the three-way 
cock was placed on lap, in which position all ports were 
blanked. The pump would continue compressing air into 
the main reservoir, to be put into the train pipe when the valve 
was again placed in service position. 

To release the brakes, the engineer placed the valve in 
release position, which allowed air coming from the train 
line and brake cylinders to pass to the atmosphere through 
the three-way cock. 

4. Defects. — With this form of brake, the brakes on the 
entire train were rendered useless if a hose burst or if the train 
broke in two, as then the air admitted into the train pipe to set 
the brakes would pass to the atmosphere through the burst hose 
instead of into the brake cylinder. Aside from this, there were 
several other serious defects in this brake. On a long train, the 
main reservoir, when connected with the train pipe and brake 
cylinders through the three-way cock, would equalize at a low 
and comparatively ineffective braking pressure, as a consequence 
of which, considerable time was required to stop a train. Again, 
air entering at the head of the train had a tendency to apply 



1 THE AIR BRAKE. 



the brakes at the head end first, and, when a sudden application 
of the brakes was made, the slack, running ahead from the rear, 
would often do serious damage to the cars and their contents. 
The effect of friction on the flow of air through the train line 
also hindered the free passage of air through the train pipe, 
causing the brake to be slow in its action, both in application 
and release. 



THE AUTOMATIC BRAKE. 

5. Automatic Air Brake. — The many defects of the 
straight-air brake led to further study, invention, and experi- 
ment, the result being the introduction of the automatic air 
brake by Westinghouse in 1873. 

The adoption of the automatic brake necessitated the 
addition of an auxiliary reservoir and plain triple valve under 
each car and tender, but did not, for the time being, affect the 
engine equipment — the brake valve, reservoir, etc. 

With the automatic brake, the necessary braking power, 
regardless of the length of the train, was stored in the auxiliary 
reservoir under each car, for use on that particular car; and, if 
a hose burst or the train parted, the triple valves would auto- 
matically apply the brakes on the whole train — something that 
could not result on a train equipped with the straight-air brake. 
Thus, a safer and quicker brake was obtained. Even this one, 
however, was found to be too slow in its action in cases of emer- 
gency, the brakes not setting with sufficient rapidity to avoid 
damage when the slack in the train ran ahead. When a quick 
reduction of train-pipe pressure was made, the head brakes 
would be set in full before the reduction reached the rear of the 
train, this retardation being due to the friction of the air in the 
long train pipe. 

The trouble thus experienced with the plain triple led to 
the invention of the quick-action triple valve that was brought 
out by Westinghouse in 1887. This valve could be sub- 
stituted for the old-style valve on trains already equipped, 
no other changes in the system being necessary, except the 
use of a larger train pipe. 



THE AIR BRAKE. § 1 



6. High-Speed Brake. — The straight-air brake is now 
practically a thing of the past; the plain automatic is used 
only on engines, tenders, and a few old-style freight equipments 
put on years ago; while the quick-action automatic is in 
general use on both freight and passenger cars throughout 
the country. 

The demand for trains having a schedule speed of more than 
50 miles an hour has made necessary a brake even more power- 
ful than the quick-action automatic. Such a one is the high- 
speed brake, as now used on fast- timed trains like the 
"Empire State," the "Black Diamond," the "Congressional 
Limited," etc. 

WESTI^GHOUSE AUTOMATIC AIR 
BRAKE. 



GENERAL ARRANGEMENT OF BRAKE. 

7. Air Pump. — The essential parts of the Westing-house 
automatic air Drake, and their arrangement on the engine, 
tender, and passenger car, are shown in Fig. 1. The air pump, 
generally placed above the right running board in front of the 
cab, consists of a steam cylinder 1 and an air cylinder 2. The 
two pistons working in these cylinders (one in each) are 
attached to the same piston rod, as seen in the figure. 
Therefore, the air piston moves up and down exactly as the 
steam piston does, and thus compresses the air to be used in 
the brake system. When the compressed air leaves the pump, 
it goes to the main reservoir and to the engineer's brake valve; 
thence, in certain positions of this valve, it passes through 
the same into the train pipe, and thence through the triple 
valves into the auxiliary reservoirs. A pressure of 90 pounds 
is stored in the main reservoir on the engine for the purpose of 
releasing brakes and recharging the auxiliaries and train pipe. 

8. Pump Governor. — The pump governor 3 is placed 
in the steam pipe leading to the pump, being located between 




8 ,r BRAKE CYLINDER. ^VAl 




ENGINEk 
FEED VA 




COUPL) 




8"3RAKE CYLINDER. , £ VAl 




NDER, ^vicocK- 

r, 




ENGINEt 
FEED VA 




§ 1 THE AIR BRAKE. 5 

it and the lubricator. It acts as an automatic throttle valve 
that stops the pump when the desired air pressure is obtained 
in the main reservoir or train pipe (to whichever it may be 
connected), and starts it again when, for any reason, this 
pressure falls below the desired amount. 

9. Main Reservoir. — This reservoir, which is usually 
placed under the engine, just back of the cylinders, is a store 
chamber in which a large supply of compressed air is main- 
tained. This supply of air is used to charge the train pipe 
and auxiliaries, and to release brakes, if set, by charging the 
train pipe to a higher pressure than that in the auxiliaries; also, 
to feed any train-pipe leaks while the brakes are released. 
The usual main-reservoir pressure is 90 pounds, but this is 
exceeded (1) in mountain districts, (2) when handling very 
long trains, (3) when the train is equipped with the high-speed 
brake, or (4) when the Westinghouse special attachment for 
controlling heavy trains on long down-grades is used. 

10. Engineer's Brake Valve. — This valve is located in 
the cab of the engine, in a position convenient to the engineer. 
Its function is to regulate the flow of air from the main reser- 
voir to the train pipe, and through chamber D in the brake 
valve to the small equalizing reservoir under the right running 
board, sometimes called the brake-valve reservoir, or "little 
drum " ; from the train pipe through the engineer's valve to the 
atmosphere; and from chamber D, the equalizing reservoir, and 
train pipe to the atmosphere; also, if desired, it prevents any 
flow of air whatsoever. The equalizing reservoir is connected 
to chamber D of the brake valve, with the object of increasing 
the volume of that chamber. Air passes through chamber D 
when going either into or out of the brake- valve reservoir. 

11. Air Gauge. — The air gauge 4 is placed in the cab in 
such a position that it may be easily seen and read by the 
engineer. It is of the duplex pattern, and really consists of 
two gauges. It has two hands or pointers — one colored red and 
the other black. The red hand indicates the main-reservoir 
pressure; the black one shows the pressure in the chamber D 



6 THE AIR BRAKE. § 1 



(of brake valve) and the equalizing reservoir, this pressure 
being generally the same as that in the train pipe. Although 
the gauge pipe leading to the black gauge hand is connected 
with the equalizing reservoir, the black hand, for reasons that 
will be explained in the study of the engineer's valve, is 
generally spoken of as indicating train-line pressure. 

12. Cut-Out Cock. — A cut-out cock 5 is placed in the 
train pipe just below the brake valve. This allows the brake 
valve to be " cut out ' ' from the train line for the purpose of 
testing, or when this particular engine is the "following" one 
of a "double-header," and the brakes are to be controlled by 
the leading engineer. 

13. Train Pipe and Attachments. — Mention has 
already been made of the train pipe. It is the pipe that leads 
from the brake valve back through the train, and is connected 
to the triple valves by means of branch pipes. It is through 
the train pipe that air, after leaving the brake valve, is con- 
ducted to the triple valves, through which valves it passes into 
the auxiliary reservoirs. The pressure usually carried in the 
train pipe is 70 pounds, except in mountainous districts and on 
trains equipped with the high-speed brake already referred to. 
The sections of train pipe under adjacent cars are connected 
by means of flexible rubber hose and suitable couplings. 

Angle cocks, for the purpose of closing the train pipe, are 
placed at each end of a car, in case it should be necessary 
to switch the car, or if for any reason it should be necessary to 
disconnect the hose, as well as to close the rear end of the train 
pipe. Angle cocks, in all modern equipments, are open when 
the handle stands parallel with the train pipe, as shown in 
Fig. 1, and closed when at right angles to it. 

The handle of the cut-out cock tf, Fig. 1, stands at right angles 
to the branch pipe when the cock is open, and parallel with it 
when closed. In very old equipments, however, the older form 
of cut-out cock is used, their handles standing crosswise of the 
pipe when open. If there is any doubt as to whether a cock 
is open or closed, glance at the crease in the top of the plug 
valve. This crease should be parallel with the pipe when the 



§ 1 THE AIR BRAKE. 



cock is open. If the brake on any car is defective, it may 
be cut out by closing the cut-out cock 6, without affecting the 
operation of the brakes ahead of, or behind, that car. 

14. Auxiliary Reservoir. — An auxiliary reservoir should 
be placed on each engine, tender, and car; the old custom of 
using one auxiliary for both engine and tender is now consid- 
ered very poor practice, and is seldom met with. The function 
of the auxiliary reservoir is to receive and store air for use in 
applying the brake on the car on which it is placed. Auxiliary 
pressure, when fully charged, is equal to train-line pressure. 

15. Brake Cylinder. — A brake cylinder, in which a 
piston operates, is placed under each car of the train. The 
brake levers are connected to the crosshead 7, Fig. 1, in such a 
way that, when air pressure is admitted to the brake cylinder 
and forces the piston out, the brake shoes are forced up to 
the wheels. 

16. Triple Valve. — This valve is connected at the junc- 
tion of the train pipe, auxiliary reservoir, and brake cylinder. 
It has three duties to perform: (1) to charge the auxiliary 
by connecting it with the train line; (2) to apply the brake 
by connecting the auxiliary with the brake cylinder; and (3) to 
release the brake by connecting the brake cylinder with the 
atmosphere. 

17. Conductor's Valve. — This valve is placed only on 
cars in passenger, mail, baggage, express service, and on 
cabooses". It is generally located at the end of the car, and is 
connected with the train line by a branch pipe. This valve is 
intended for the trainmen's use, so that they may have the 
power to stop the train in case of an emergency of which the 
engineer is ignorant. A cord running the full length of the car 
is connected to this valve; when this cord is pulled, it opens 
the valve and allows air to escape from the train pipe, which 
causes the brakes to apply. 

1 8. Drain Cups. — These cups are placed on all engines, 
tenders, and cars. Each drain cup contains a screen to keep 
dirt and other foreign matter from reaching the triple. The 



8 



THE AIR BRAKE. 



§1 



drain cup on the tender is made larger, as it collects consider- 
able moisture, which should be drawn off through the drain 
cock after each trip. 



MAIN RESERVOIR. 



19. The main reservoir (Fig. 1) is an air-tight cylinder 
having a pipe connection with the pump and also one with the 
engineer's brake valve. 



SIZE. 



20. Main reservoirs vary in size according to the kind of 
service — freight or passenger — in which the engine is employed. 
The following table gives the standard sizes: 



STANDARD SIZES OF MAIN RESERVOIR. 



Outside Dimensions. 


Capacity. 
Cubic Inches. 


Length. 
Inches. 


Diameter. 
Inches. 


221 


34 


11,200 


24J 


34 


14,000 


261 


34 


15,800 


20i 


41 


12,200 


22i 


41 


14,000 


24i 


41 


17,400 


26J 


41 


20,000 



In the best practice, a main reservoir of not less than 16,000 
cubic inches capacity for passenger, and 20,000 for freight, 
service is used. 

A larger main reservoir is necessary on freight than on 
passenger engines, (1) because of the greater number of air 
cars handled in a train in freight service; (2) because there is 
a longer train pipe and more auxiliaries to recharge after the 
brakes are released; and (3) because the greater the volume of 
air in the main reservoir, the higher the pressure at which the 



§1 THE AIR BRAKE. 



main reservoir and train pipe will equalize, and the easier, 
therefore, it will be to release brakes. 

It is often found that when a pump is heating, the trouble 
will disappear entirely if the capacity of the main reservoir is 
increased. If the train is long and the main reservoir small, a 
high pressure must be carried in the latter in order that it may 
equalize with the train pipe at a sufficiently high pressure to 
promptly release the brakes and recharge the auxiliaries. When 
the main reservoir is large, a much lower reservoir pressure can 
be carried, and the pump can also store a greater quantity of 
air while the brakes are applied. When, therefore, the main 
reservoir is small, the pump must work both faster (or longer) 
and against a higher pressure, and either of these tends to cause 
Overheating. 

LOCATION. 

21. The main reservoir is usually located between the 
frames, back of the cylinder saddle. This is the most approved 
location, although it is sometimes found advisable to sacrifice 
the location in order to use a main reservoir of the desired 
capacity. It should, if possible, be located lower than the air 
pump in the brake system on the engine, in order that all dirt, 
oil, and moisture will settle there. Then it may, and should be, 
drained after each trip, a drain cock being provided in the 
bottom of the reservoir for this purpose. When water is 
allowed to accumulate in the main reservoir, it not only reduces 
the space available for storing air, but if the pipes of the brake 
system are not properly arranged on engine, it will work back 
into the brake system, carrying dirt and oil with it, which gums 
up the brake valve and triples and prevents the brakes from 
working properly. There is also danger, in winter, of the water 
freezing and stopping up the pipes. The water that gets into 
the brake system is mostly drawn into the air end of the pump 
with the air. This is especially true on damp and rainy days. 
The main reservoir is sometimes located between the frames 
under the deck, sometimes on top and at the back of the 
tender, and frequently under the cab running board. It is 
also occasionally seen on top of the boiler, back of the bell. 



10 THE AIR BRAKE. gl 

When the main reservoir is located on the tender, it is neces- 
sary to run a line of pipe from the pump back to the tender, 
and a return pipe from the main reservoir to the engineer's 
valve. This proves rather expensive, the more especially as 
dirt and moisture settle in the hose connections between engine 
and tender and soon destroy them. 

The objection to placing the main reservoir between the 
frames under the deck is that the reservoir is in the way when 
working at the wedges, boxes, and dampers. 

It is not unusual to use two small main reservoirs, in which 
case the air should go from the pump to one of them, thence 
passing into the second one, and from there to the brake valve. 



DUPLEX AIR GAUGE. 

22. A duplex air gauge, which indicates both train- line 
and main-reservoir pressures, is located in the engine cab, in a 
position convenient for the engineer to see. This gauge, shown 
in views (a) and (6), Fig. 2, consists really of two gauges com- 
bined in one, the same dial serving for both hands. The 
right-hand gauge, which, as seen, connects with T, operates the 
black hand. This hand is said to represent train-line pressure, 
although T really has a pipe connection to chamber D and the 
equalizing reservoir at W, Figs. 14 and 16; but the study of the 
engineer's valve will develop the fact that equalizing-reservoir 
and train-pipe pressures are usually equal. The other con- 
nection M, a part of the left-hand gauge, is piped to R, Figs. 14 
and 16, so that this hand, colored red, indicates main-reser- 
voir pressure. 

23. Principle of Working. — An inside view of the air 
gauge is shown at (6), in which A and B are two bent tubes of 
elliptical shape, as shown at (d). The tube B is connected to 
the fitting T, and the tube A to the fitting M. The bottom 
ends of the tubes are held fast, but the top ends are free. 

The action of the gauge may be thus explained: If a 
tube of elliptical section is bent as shown in view (d), and then 



12 THE AIR BRAKE. 



subjected to an internal pressure (of either a gas or a liquid), 
the force exerted will tend to straighten the tube. This is due 
to the fact that the force exerted within the tube tends to make 
it assume the circular form shown dotted in view (c). In 
assuming the circular form, the concave side a of the bent tube 
tends to lengthen, while the convex side b tends to shorten. 
These combined efforts tend to straighten the tube out, and 
therefore impart a movement to its free end. 

Tube A is connected to one end of the lever kj by means of 
the link c. This lever is pivoted at e, and the end j forms a 
toothed sector that meshes with a pinion on the spindle i. 
The spindle i carries the red hand, or pointer, of the gauge, 
and rotates within a hollow spindle I, which carries the 
black hand. Tube B is connected by link b to the lever 
fg at a point below the fulcrum, or pivot, so that the black 
hand will be turned in the same direction as the red one. 
The lower end of the lever fg takes the form of a toothed 
sector that meshes with a pinion on the hollow spindle I 
and operates the black hand. 

24. Operation of Gauge. — Since the main reservoir 
connects with 31, air under pressure enters tube A and tends 
to straighten it out. This causes the free end of A to move to 
the left, drawing the link c with it, thus moving the toothed 
sector j to the right. As this sector engages with the spindle % 
the latter is made to move clockwise — that is, to have a motion 
in the same direction as the hands of a clock. The. red hand 
is also given a similar motion. 

Train-pipe pressure acts within the tube B to straighten it, 
and the free end is moved to the right. As the bar b is con- 
nected below the fulcrum of the lever fg, the movement of the 
free end B will cause the toothed sector g to move to 
the right and turn the black hand clockwise also. The 
greater the pressure within the tubes, the greater will be the 
tendency for them to straighten out, and the higher will be 
the pressure registered by the gauge; d and h are small coiled 
springs to take up the play or backlash in the teeth of the 
sector and pinion. 




36 



Fig. 3. 



§ 1 THE AIR BRAKE. 13 



PUMP GOVERNORS. 



DESCRIPTION. 

25. The operation of the old style of pump governor, 
Fig. 4, is so nearly similar to that of the improved type, Fig. 3, 
that a description of the latter will suffice for both. The 
characteristics of the two governors will be considered later on. 

The steam-supply pipe to the air pump leads from the top of 
the dome to a throttle, usually conveniently situated in the cab. 
From the throttle, the pipe leads to the steam connection X, 
Figs. 3 and 4, of the pump governor, the other connection Y 
of which is piped to the pump, as shown in Fig. 1. In order to 
reach the pump, all steam must pass through the pump gov- 
ernor, whose function is to shut off steam from the pump when 
the desired air pressure is obtained, and to admit it again 
when the air pressure falls below the amount desired. 

When used in connection with a D-8 engineer's brake valve 
having an excess-pressure valve, the governor is connected to, 
and operated by, train-pipe pressure, the pipe connection being 
made to z, Figs. 3 and 4. When used with the F-6 brake valve 
having the feed- valve attachment, the governor is operated by 
main-reservoir pressure, the pipe connection to the governor 
being made at z, as before. 

26. Referring to Fig. 3; it will be seen that chamber a is in 
direct communication with the pipe connection z that leads to 
the main-reservoir pressure when used with the F-6 brake valve. 
Ip2 is a brass diaphragm that, in moving, operates the pin 
valve b. 41 is a regulating spring that tends to drive the 
diaphragm 4-2 down with a force just a trifle less than the pres- 
sure in a at which the governor is intended to operate. 28 is 
the governor piston, to which the steam valve 26 is attached by 
means of its stem and the locknuts. 31 is the piston spring, 
whose duty is to hold the steam valve 26 from its seat when 
there is no air pressure above piston 28; it does this by forcing 
the piston upwards, carrying the valve 26 along. 29 is a 
packing ring, made a sufficiently good fit -to prevent any serious 



14 THE AIR BRAKE. § 1 



leakage of air from chamber e past the piston. In the old style 
of governor, Fig. 4, the packing ring 24. was made loose so that 
air would leak past piston 5. This point, however, will be 
taken up again when describing the operation of the governor. 

The dotted circles seen below governor piston 28 show where 
the drip-pipe connection 36 is made. The position of the drip 
pipe on the old governor is also shown by dotted circles. The 
object of a drip pipe is to permit the escape to the atmosphere 
of any air that leaks past the ring 29 or of any steam that leaks 
up by the stem of the steam valve 26, instead of allowing it to 
collect under piston 28. 

A small port/ is drilled in the new governor steam valve 26. 
Its purpose is to maintain a circulation of steam in the supply 
pipe, and to keep the pump working slowly, thereby keeping 
the latter warmed up and preventing, to a great extent, the 
condensation of steam when the pump is started. If the pump 
were inactive for some time after full main-reservoir pressure 
had been attained, steam would condense, and the condensation 
would be thrown out of the stack, upon the engine jacket, when 
the pump next started to work. 

In the following explanation, it will be assumed that the 
governor is to be used with the F-6 brake valve, and, therefore, 
is operated by main- reservoir pressure. 



OPERATION OF GOVERNOR. 

27. The regulating spring 41 is, as a general practice, 
adjusted so that it will just withstand a main-reservoir pressure 
of 90 pounds pushing upwards on the diaphragm £2 (see 
Fig. 3). When the pump is in operation, the pressure in the 
main reservoir, and, consequently, in chamber a of the governor, 
increases until a pressure of 90 pounds is reached. When the 
pressure in chamber a just slightly exceeds the pressure exerted 
by the regulating spring ^i, the diaphragm 42 is raised, carrying 
the pin valve b with it. The air in chamber a passes by 
the unseated pin valve b, down through port d, and into 
chamber e on top of the piston 28, forcing it down and thus 
seating the steam valve 26. As long as main-reservoir pressure 




Fig. 4. 



§ 1 THE AIR BRAKE. 15 

remains at 90 pounds, the diaphragm Jf2 will hold the pin 
valve b from its seat, and the pressure in chamber e will hold 
the steam valve 26 to its seat. If the main-reservoir pressure 
falls below 90 pounds, the thrust of the spring tending to force 
the diaphragm 4® down will overcome that of the air in cham- 
ber a tending to force it up. Consequently, the diaphragm 
will move downwards and thus seat the pin valve b. 

This shuts off the air supply from chamber e, and the air 
confined therein by the pin valve closing will escape to the 
atmosphere through the relief port c. The pressure now being- 
removed from above the piston 28, the spring 31, aided by the 
steam under valve 26, forces the piston upwards, unseating 
valve 26, and allowing steam to pass through the governor 
to the pump. The piston 28 is made sufficiently larger than 
the steam valve 26 to enable a moderate air pressure to easily 
hold valve 26 to its seat against the combined upward force of 
the steam pressure under the valve and the push of spring 31. 

28. The operation of the governor is the same, whether 
used with the F-6 or with the D-8 brake valve. In the former 
case, however, the governor is operated by main-reservoir pres- 
sure; whereas, in the latter case, it is operated by train-pipe 
pressure. In this case, the spring 41 must be adjusted to just 
withstand an upward pressure on the diaphragm 42 equal to 
train-pipe pressure, usually 70 pounds. 

In the old-style governor, as soon as the pin valve 17 closes, 
the air entrapped above piston 5 leaks by the packing ring 24 
(which is purposely made a loose fit), and escapes through the 
waste-pipe stud 10 located in the casting, as shown by the 
dotted circles. The rapidity with which the air above piston 5 
will escape and permit the governor to operate, depends on the 
fit of packing ring 24. In some cases, the leakage is so slow 
that fully half a minute elapses after the pin valve is closed 
before the governor starts the pump. 

The improved governor is provided with a relief port c, 
Fig. 3, the object of which is to enable the governor to start the 
pump promptly when the pressure in chamber a allows the pin 
valve b to close. The relief port communicates with chamber e, 



16 THE AIR. BRAKE. § 1. 

and is of such a size as will, in two seconds after the pin valve 
closes, release sufficient air from above piston 28 to enable the 
governor to start the pump. This port permits a constant leak- 
age of air from chamber a as long as the pin valve is open, 
which is usually sufficient to keep the pump running slowly. 

The small port / drilled through the steam valve 26 in the 
improved governor is provided, as has already been stated, to 
allow sufficient steam to pass to the pump when the steam 
valve is closed, to make the pump take a stroke or two occa- 
sionally, thus keeping it warmed up. In the old governor, the 
pump ceases to work after full pressure is attained, except so 
far as may be required to supply any leaks in the brake 
system that would otherwise reduce the train-pipe pressure 
below 70 pounds. 

THE 8-IXCH AIR PUMP. 

29. Fig. 5 shows a cross-sectional view of the Westinghouse 
8-inch air pump as used at the present time. In the 
illustration, 3 is the steam cylinder, and 2 its head; ^ is the 
centerpiece that forms the bottom head of the steam cylinder 
and also the top head of the air cylinder, 6 being the lower head 
of the latter cylinder. 

We shall first describe the steam cylinder and head, and 
explain its mode of working— then deal with the air cylinder. 



THE STEAM CYLIXDEK. 

30. Description. — On referring to Fig. 5, two pistons 7 
and 7' of unequal diameters will be observed, connected together 
by the stem 7", the whole forming what is known as the main 
steam valve; 8 and 9 are the upper and lower main- valve 
packing rings, respectively; 10 is the steam piston and 10' the 
piston rod, to the lower end of which is connected the air 
piston 11. The steam end of the piston rod 10' is made hollow 
to receive the reversing rod 17, which works up and down inside 
it. 12 and IS are piston packingT rings; 23 is the reversing 
piston, which is £ inch larger in diameter than piston 7; 24 is 




Fig. 5. 



THE AIR BRAKE. 17 



the reversing-piston packing ring; and 16 is the reversing slide 
valve, which is brought into play to reverse the movement of 
the steam piston 10. 

31. The niain valve, which is also, called a differential 

valve, controls the admission to, and the exhaust of steam 
from, cylinder 3. It works inside the bushings 25 and 26, 
contained inside chamber m, one at each end. Each bushing 
has two rows of ports (circular holes) s, e, and s', e' , respect- 
ively. The ports s and s' are the admission ports, and e and 
e' are the exhaust ports. The stop-pin 50 prevents the main 
valve from dropping below the bushings 25 and 26 far euough 
for the packing rings 8 and 9 to expand and so prevent the valve 
from taking an upward stroke. The steam-supply pipe from 
the pump governor is connected to the pump at X, and, all the 
time the pump is operating, chamber m is full of steam, and 
acts as a steam chest for the steam cylinder 3. Port h in 
chamber m leads to chamber I in the reversing- valve bushing 
19, which serves as a steam chest to furnish steam to the space 
above the reversing piston in chamber d. The reversing 
valve 16, which works inside the re versing- valve bushing 19, 
moves up and down with the reversing rod 17, any move- 
ment of the rod causing a corresponding one in the reversing 
valve. The reversing piston 28 works in the bushing 22, 
and has a stem that passes through the bushing and bears on 
the main valve stem 7" . 

32. The upper end of the reversing rod works freely inside 
the cap nut 20. One end of port x opens into the top of the 
cap nut, and the other end connects with a passage that runs 
down alongside the reversing- valve bushing 19 and thence into 
top of steam cylinder 3. This port, in conjunction with the 
passage, serves two purposes: it prevents both a back pressure 
and also a vacuum from forming in the cap nut above the end 
of the reversing rod as the latter works up and down; and it 
also allows steam to work through from steam cylinder 3, and 
thus supply the necessary lubrication for the rod end. 36, 37, 
38, and 39 are copper gaskets, forming the joints between the 
cylinders, heads, and centerpiece, as shown. Jfl is a drip cock 



18 THE AIR BRAKE. §1 



that should be opened when the pump is first started, to get 
rid of any condensation. 56, 56 are the gland nuts. 

33. Operation of Steam Cylinder. — When the pump 
is not working, there is a tendency for the steam and air pistons 
and also the main valve and reversing valve to settle down to 
their lowest positions. 

When the pump throttle is first opened, steam enters chamber 
m and exerts an upward pressure on piston 7, and a downward 
pressure on piston 7\ Since the area of piston 7 is greater than 
that of piston 7', the steam pressure would force the main valve 
upwards, were it not for the fact that steam from chamber m 
passes through port h into chamber I in the valve bushing 19, 
and thence through port a into chamber d above the reversing 
piston 23. The downward pressure that the steam exerts on 
piston 23 is transmitted through its stem to the main valve 7", 
and it thus balances the upward push of the steam in chamber 
m on piston 7, as both pistons are nearly the same size, and 
are acted on by the same steam pressure. The two upper 
pistons 23 and 7 being thus nearly balanced, the downward 
pressure acting on the small piston 7' suffices to hold the main 
valve down in the position shown. While in this position, 
steam from chamber m passes through the lower admission 
ports s' into the steam cylinder underneath piston 10, forcing it 
up. Any steam that is above the piston 10 passes through the 
exhaust port e of bushing 25, thence on into the exhaust passage 
//across the top head of the pump, as shown by the dotted lines, 
into the chamber g and out to the exhaust at Y. Just before 
piston 10 reaches the end of its upward stroke, the reversing 
plate 18 strikes the shoulder j on the reversing rod 17, and the 
rod and reversing valve 16 are moved upwards until the valve 
16 closes port a, and, by means 'of the cavity/, connects the 
exhaust port b with port c. The steam above the reversing 
piston 23 now exhausts through port b, exhaust cavity ?', and 
port c, thence through the exhaust passage // into chamber g, 
and out at Y. The pressure is thus exhausted from chamber d; 
and, as the upward force exerted by piston 7 of the main 
valve is greater than the downward force exerted by piston 



§1 THE AIR BRAKE. 19 



7', the main valve moves upwards, closing ports s' and e, and 
opening ports s and e' '. Steam from chamber m then passes 
through the steam ports s into the steam cylinder above piston 
10, which, consequently, is forced downwards. The steam below 
piston 10 passes out through the exhaust ports e' in bushing 
26, through the passage f f into g, and thence out of the 
exhaust at Y. 

Just before piston 10 reaches the end of its downward stroke, 
the under side of the reversing plate 18 strikes the button u on 
the end of the reversing rod 17, and the reversing valve 16 is 
moved down to the position shown. This closes the exhaust 
port b, and opens the steam port a, admitting steam once more 
from chamber /, through port a into chamber d. The combined 
downward pressure on the reversing piston 23 and the piston 7' 
is now greater than the upward force acting on piston 7, and 
the mam valve moves down, so that steam from chamber m is 
again admitted through ports s' into the cylinder below 
piston 10, forcing it upwards once more, the ports e exhausting 
the steam from above the piston. This completes a full stroke 
in the steam end of the pump. 



THE AIR CYLIXDER. 

34. Description. — In the air cylinder, as shown in 
Fig. 5 3 31 and 33 are the receiving valves; 30 and 32 are 
the discharge valves. The port p' leads from the bottom end 
of the air cylinder to the space between the valves 32 and 33, 
and port p leads from the top end of the air cylinder to the 
air space between valves 30 and 31. The space t above the top 
discharge valve 30 is in direct connection with chamber w, by 
means of a passage in the body of the cylinder, which enters 
this chamber at r. Air enters the lower end of the cylinder 
through the air inlets in the lower valve-chamber cap 34, and 
air for the upper end of the cylinder enters through the air 
inlets r, just below the receiving valve 31. 

35. The receiving- valAes should have a lift of ^ inch, 
and the discharge valves one of X inch. The lift of the 



20 THE AIR BRAKE. 



valve 30 is regulated by the distance between it and the cap nut 
29; the lift of valve 81 is regulated b}^ the distance between the 
top of itself and the bottom of valve 30; the discharge- valve 
stop 44 regulates the lift of valve 32, and is itself held in 
position by the setscrew 45. The lift of valve 33 is regulated 
by the distance between itself and the bottom of valve 32; 40 
is the oil cup through which the air cylinder may be oiled. 
If the cup is filled and the cock opened while piston 11 is 
descending, the oil will be drawn in; or, oil may be poured 
in when the pump is idle. 

36. Operation of Air Cylinder. — As the steam piston 
is forced up and down, the air piston 11 is carried with it. 
When the air piston 11 is on its up stroke, the air above the 
piston is compressed and the tendency is to form a partial 
vacuum below the piston. The air compressed above the piston 
passes through port pp and in between the valves 30 and 31, 
forcing the latter on to its seat and, as soon as the pressure 
beneath valve 30 is greater than the main-reservoir pressure on 
top of it, forcing this valve from its seat, and flowing into 
space t, thence into port r and down into chamber w, from 
whence it passes out at Z into a pipe leading to the main 
reservoir. Main-reservoir pressure in chamber iv is holding the 
lower discharge valve 32 on to its seat, and just as soon as 
the partial vacuum under piston 11 (due to its upward 
movement) is sufficiently great, the pressure of the atmosphere 
forces the lower receiving valve 33 from its seat and passes 
through port p' into the cylinder, filling the space beneath 
piston 11 with air at atmospheric pressure. 

By the time the air piston has reached the top of its cylinder, 
the main valve will have made its upward stroke and cut off 
steam from the bottom side of steam piston and admitted it to 
the top, thus reversing the motion of the steam piston and, 
therefore, of the air piston also. As the air piston moves down- 
wards, it tends to form a partial vacuum behind it, and to 
compress the air in front of (i. e. beneath) it. The air that is 
being compressed below the piston passes through port p' , 
forcing the receiving valve 38 to its seat, and, as soon as the 



THE AIR BRAKE. 21 



pressure beneath the lower discharge valve 82 is greater than 
the (main-reservoir) pressure in chamber w above it, forcing this 
valve from its seat and flowing into chamber w and out to the 
main reservoir at Z. As already mentioned, a partial vacuum 
has been formed in the space above piston 11 and in port pp, 
and atmospheric pressure forces air in to fill this space, entering 
the holes at v, and raising the top receiving valve 31 from its 
seat, thence passing through port pp and filling the upper part 
of the air cylinder with air at atmospheric pressure. The 
motion of the pump is again reversed as the piston nears the 
bottom of the cylinder, and, in moving upwards, it compresses 
the air that has just been "sucked in" above the piston and 
forces it into the main reservoir. A complete cycle of the 
movements of the pump has now been traced. 



THE 91-r^CH AIR PUMP. 

37. As the custom of equipping freight cars with the air 
brake became more and more general, an engineer often found 
himself called on to handle as many as 60 air-brake cars in 
a single train; it therefore became imperative that a pump of 
greater capacity than the old 8-inch pump should be employed. 
To meet this demand, the 9 f --inch air pump was brought out. 

38. Three views of the Westinghouse 9|-incli air pump 
are given in Fig. 6. (a) is a cross- sectional view, showing the 
front half of the pump removed; an additional portion of the 
centerpiece and air cylinder xyz is also shown broken away, so 
that a view of the discharge air-valves, valve cases, and air 
passages may be presented. (6) is a side view, showing a 
section through the valve gear in the upper steam-cylinder 
head; a portion of the steam cylinder also is shown broken 
away, (c) is a back view, in which portions of the steam and 
air passages and of the air-valve cases are broken away to give 
a clearer idea of the location of the valves, ports, and passages. 
The steam-supply pipe is connected to the pump at X, the 
exhaust pipe at F, and the air-discharge pipe to the main 
reservoir at Z. 



22 THE AIR BRAKE. § 1 



THE STEAM CYLINDER. 

39. Description. — In Fig. 6, 61 is the steam cylinder and 
63 the air cylinder. The steam piston 65 and air piston 66 
are connected by piston rod 65' , the upper part of which is 
hollow, as in the 8-inch pump. In the 9|-inch pump, all the 
steam valve gear, except reversing rod 71, is contained within 
the upper steam-cylinder head 60. This is a great convenience, 
for, should the valve gear get out of order, a new head can 
be substituted for the defective one in a few minutes. 

Three views of the main-valve bushing 75 are given, 
namely, a longitudinal section in view (a), a transverse section 
in view (6), and an outside elevation in view (ri), showing the 
bushing removed from the steam-cylinder head. In this latter 
view is also shown the main-valve head 85. The ports b and c 
pass through the bashing, and are the steam ports for the slide 
valve 83, views (a) and (6). The port d also passes through 
the bushing, and is the exhaust port for the slide valve 83. 
The groove /' connects with the exhaust port d. Grooves h' 
and g' connect with the ports h" and g", which open into 
chamber B, the space between piston 77 and the cylinder 
head 84-. A passageway t in the bush and t' in the main-valve 
head 85 (represented by dotted lines) establishes communica- 
tion between chamber E in the main-valve head and the 
exhaust groove /; chamber E, therefore, is in constant com- 
munication with the atmosphere through passages t' and t, 
groove /, and exhaust port d. Any steam that may leak past 
the piston 79 is thus prevented from accumulating in cham- 
ber E, where it would prevent the main valve 76 from taking a 
stroke to the left. The port a" connects chamber A — the space 
within the bushing 75 — with the steam-supply passage a' a, 
views (6) and (c); consequently, this chamber, which acts as a 
steam chest for the slide valve 83, is always filled with steam 
as long as steam is turned on to the pump. Port e connects 
with the passage e' , which leads into the reversing-valve 
bushing 73; therefore, this bushing, which acts as a steam chest 
for the reversing valve 72, is also filled with steam as long as 
the pump is supplied with it. 



§1 THE AIR BRAKE. 23 

The steam port b in bushing 75 connects with the steam pas- 
sage b' b", which opens into the lower end of the steam cylinder 
below the piston at b'" , views (a), (6), and (c). The other 
steam port c connects directly with the upper end of the steam 
cylinder through the passage c'. The exhaust port d connects 
with the passage d! d", views (a) and (c), which leads to the 
atmosphere through the exhaust connection Y. 

40. Steam enters the pump at X, flows through the passage 
at ««', views (6) and (c), and enters the main-valve bushing 
through the port a". Three ports /, h, and g, in the reversing- 
valve bushing 73, connect directly with the grooves/, h! , and g' , 
in the main-valve bushing 75, views (6) and (d). A reversing 
valve 72, having a cavity i in its face, operates inside the 
bushing 73. The duty of this valve is to admit steam to, 
and exhaust steam from, the space B between the piston 77 
and head 81f, immediately before the piston valve 76 takes its 
stroke toward the left or right, respectively. The reversing 
valve 72 is held between two shoulders on the reversing 
rod 71, so that if the rod is moved up or down, it moves the 
valve with it, as in the 8-inch pump. When the reversing 
valve is in the position shown in view (b), it closes port g, and 
the cavity i connects port / with port h; hence, chamber B is 
open to the atmosphere, and any steam in there can exhaust 
through port h" , groove h', port h, cavity i in slide valve, port/, 
groove /, and exhaust port d. When the reversing valve is 
moved up to its highest position, port g is open and the part k 
of the valve covers ports /and h. Steam can now flow through 
port g, groove g' , and port g" into chamber B, whence it cannot 
escape into the exhaust, owing to the ports /and h being closed. 

4 1 . The main valve 76 consists of two pistons 77 and 79 of 
unequal diameter, connected by the valve stem 81. The small 
piston 79 works to and fro in the main- valve head 85, piston 77 
working in the main- valve bushing 75. The slide valve fits 
between two shoulders on the main- valve stem 81, and, there- 
fore, whenever the piston valve moves, it carries the slide 
valve with it. 



24 THE AIR BRAKE. § 1 

42. It is thus seen that the 9^-inch pump contains three 
steam valves: the slide valve 83; the main valve 76, called a 
differential piston valve; and the reversing valve 72. The 
duty of the slide valve 83 is to regulate the admission of steam 
to, and the exhaust of steam from, the upper and lower sides of 
the piston 65, as required. It is a valve of the ordinary D 
type, and is similar to the slide valve of a locomotive; how- 
ever, as in the case of the latter valve, some means must be 
provided for moving it back and forth as required, and it is 
the duty of the main valve 76 to so move it. 

The duty of the reversing valve 72 is to admit steam to 
chamber B when the main valve is to make a stroke to the 
left (i. e. as viewed in the illustration) and to exhaust the steam 
therefrom when the main valve is to make a stroke to the right. 
If the steam is exhausted from chamber j^ the main valve 
will naturally take a stroke to the right, since the steam in 
chamber A, which acts on both pistons, exerts a greater force 
on the larger piston 77. To make the main valve take a stroke 
to the left, it is necessary to admit steam into chamber B; this 
acts against, and balances, the pressure exerted on piston 77 by 
the steam in chamber A, and the pressure of the steam on the 
small piston 79 will then move the main valve to the left. 

43. Operation of Steam Cylinder. — When the pump 
is at rest, the pistons 65 and 66 generally settle to the bottom 
of their cylinders, and the reversing plate 69 strikes against the 
button u on the reversing rod 71 and pulls the reversing valve 
72 down into the position shown in view (b). As soon as 
steam is admitted to the pump, it enters chamber A in the 
main-valve bashing, forces the main valve to the right, as 
shown in view (a), passes down through port b and passage b' b" ', 
views (a) and (c), and enters the cylinder below piston 65 
through the ports b'" , forcing the piston upwards. Any steam 
that may be above the piston 65 will exhaust through the 
passage c', port c, the cavity in the slide valve, port d, pas- 
sage d' d", and out at Y. As the steam piston 65 nears the end 
of its upward stroke, the top of the reversing plate 69 strikes 
the shoulder j on the reversing rod 71, and forces reversing 



§ 1 THE AIR BRAKE. 25 

valve 72 upwards until it opens port g, and the part k of the 
valve covers ports h and /. This permits steam to enter 
chamber B and balance the pressure on piston 77 of the main 
valve, and the pressure on piston 79 then forces the main valve, 
and with it the slide valve 83, to the left until the cavity of the 
slide valve 83 connects port b with exhaust port d. When 
the slide valve is in this position, the steam port c is uncovered 
and steam from chamber A flows down through the passage c c r , 
into the steam cylinder above the steam piston, forcing the 
piston downwards. The steam below the piston then flows 
through the ports b'" , up through passage b" b' and port b, 
views (a) and (c), through the cavity in the slide valve, down 
through port d and passage d' d" , and out of the exhaust at Y. 
As the piston nears the end of its downward stroke, the bottom 
of the reversing plate 69 strikes the button u on the reversing 
rod 71 and pulls the rod and reversing valve downwards to the 
position shown in view (6). This movement of the valve, as 
already explained, exhausts the steam from chamber B, and 
allows the piston valve 76 to move the slide valve to the right 
into the position shown, thus permitting steam to pass under- 
neath piston 65 and force it upwards. What next occurs, 
during the upward stroke, has already been explained. The 
reversing cap nut 74, which acts as a guide for the reversing 
rod 71, has a passage x that connects with another passage 
leading into the upper end of the steam cylinder. As in the 
8-inch pump, this passage prevents either a back pressure or a 
vacuum from forming in the cap nut, and it also admits steam 
above the reversing rod, thus insuring a certain amount of 
lubrication for the rod end. Two drain cocks 105 and 106, 
located in the steam passages b" and a, are provided for the 
purpose of removing condensed water. They should be opened 
when the pump is first started and kept open until it is 
thoroughly warm. 96, 96 are the gland nuts by means of 
which the piston-rod packing is adjusted. 



26 THE AIR BRAKE. 



THE AIR CYLINDER. 

44. Description. — A side view of the air cylinder 68 is 
shown in view (6) Fig. 6; a rear view will be seen in (c); 
while view (a) shows the cylinder with the front half removed 
and a portion of the rear half broken away, so as to show the 
discharge air-valves and passages. The piston 66 is broken 
away at a b so that port p — where passage p' enters the air 
cylinder — may be seen. The receiving air valves are contained 
within the valve cases C and D. The lift of both the receiving 
and discharge valves of this pump should be -^ inch. Air 
enters the upper end of the cylinder through ports m, and the 
lower end through ports n. The air leaves the upper end of 
the cylinder through ports r, and the lower end through ports p, 
passing in each case into chamber G, and thence out through Z 
to the main reservoir. An oil cup 98 is provided, through 
which oil may be supplied to the air cylinder. Oil maybe 
poured through this cup while the pump is standing still, or it 
may be filled and the cock opened when the air piston is on its 
downward stroke; the partial vacuum in the upper end of the 
air cylinder will then cause the oil to be forced into the cylinder 
by the atmospheric pressure. 

45. To remove the top steam-cylinder head 60, it is neces- 
sary to raise the steam piston 65 in its cylinder until the 
reversing rod 71 can be disengaged from the piston and 
reversing plate. In order that the pistons may be easily 
raised, the plug 112 in air-cylinder head is provided on a 
number of pumps. A bar can be used through this opening, 
and the pistons raised very readily. This plug opening is 
useful in other ways also, as it enables the lower end of the air 
cylinder to be cleaned and the piston-rod nuts to be inspected. 
The pipe to the main reservoir is connected at Z, and main- 
reservoir pressure, therefore . is always acting to hold valves 87 
and 87' on their seats; to unseat them, the pressure below the 
valves must be greater than main-reservoir pressure. 

46. Operation of Air Cylinder. — When the air piston 
66 makes an upward stroke, it causes a partial vacuum to be 



THE AIR BRAKE. 27 



formed below it, while the air above is compressed. Air then 
flows in through the screened inlet W, and passes downward 
through the passage F, view (c), then through the receiving 
valve 86' and ports n, as shown by the arrows, into the lower 
end of the air cylinder, filling it with air at atmospheric pres- 
sure. In the meantime, the air that is compressed above the 
piston holds receiving valve 86 on its seat, and passes out 
through ports r and the passage r' to the under side of discharge 
valve 87, and, as soon as its pressure exceeds that in the main 
reservoir, raises valve 87 and flows through the passages s and G 
and out at Z to the main reservoir, as shown by the arrows. 
On the downward stroke of the air piston, a partial vacuum is 
formed above, and the air is compressed below it. Air then 
flows in through W and passes up the passage F, through 
receiving valve 86 and ports m, and fills the upper part of the 
cylinder with air at atmospheric pressure. 

' As the air is compressed below the piston, it holds receiving 
valve 86' on its seat, and passes out through ports p and 
passage p' to the under side of discharge valve 87', and, as 
soon as it exerts a pressure slightly greater than main- reservoir 
pressure, opens valve 87' and passes up through passage G and 
out at Z to the main reservoir. 



THE PIjAIX TRIPJLE VALYE. 
GENERAL REMARKS. 

47. As mentioned in the introductory portion of this 
Section, the straight-air brake was in due time supplanted by 
the automatic brake. The essential part of the new style of 
brake was the triple valve, now known as the plain triple 
valve, to distinguish it from a later form known as the quick- 
action triple valve, to be described later. The plain triple is 
still in use on engines and tenders, and also on some of 
the very early car equipments. It is practically the same as the 
service part of the present quick-action triple, that is, the 
part of the latter that is used in making a service application 
of the brakes. These two kinds of triples are somewhat 



28 THE AIR BRAKE. § 1 

differently constructed, but the results, actions, and parts 
employed in making a service application of the brakes are 
practically identical in each case. When the plain automatic 
triple was introduced, a great many cars were equipped with 
the straight-air brake, and it was necessary to so construct a 
triple valve that, if put in a train with a number of straight-air 
cars, the automatic feature of the triple could be cut out, and 
the brakes on that car used u straight air," as on the other cars. 



DESCRIPTION. 

48. In Fig. 7 are shown cross-sectional views of the plain 
triple valve introduced to accomplish the above purpose. The 
plug valve 13, which effects the required changes, is actuated by 
the handle 15. This handle may be placed in any one of the 
three positions 15, 15' , or 15" , shown in the cut. As it now 
stands, in position 15, the triple can be used with the automatic 
brake. When the handle stands in position 15' , the plug valve 
IS is moved so that the portions p, I, and i, of the plug cover the 
ports a, f, and d; the brake is then cut out entirely on that car. 
With the handle in position 15" pointing downwards, the 
passage e in valve 13 connects port a with port d, thus enabling 
the triple to be used in the straight-air system. However, now 
that the straight- air brake is a thing of the past, a lug, not 
shown in the figure, is cast on the handle 15, which prevents 
the handle from being turned to position 15" to convert the 
brake into "straight air." 

49. The other parts of the triple valve, as numbered in the 
figure, are: 1, the triple body; £, the drain cup; 3, the triple 
slide valve; 4-, the slide-valve spring; 5, the triple piston; 
6, the triple-piston packing ring; 7, the graduating valve; 
#, the upper cap nut; 9, the graduating stem; 10, the gradu- 
ating spring; 11, the graduating-stem nut; and 12, a leather 
gasket. The space marked C is called the slide-valve chamber; 
g is the exhaust cavity in the face of the slide valve 3; k is the 
triple exhaust port; m is a small feed groove in the piston 
bushing; and n is a groove in the shoulder of the triple piston 
itself. These grooves m and n allow air from the train line to 




Emergency Position. 



§ 1 THE AIR BRAKE. 29 

feed into the auxiliary reservoir when the triple piston is in 
release position. This piston 5 is acted on by pressure on both 
sides of it, moving away from the greater pressure when the two 
pressures are unequal, or remaining stationary when these pres- 
sures are equal. The branch pipe from the train line connects 
with the triple at W; the pipe leading from the brake cylinder 
connects at X, while the connection to the auxiliary reservoir 
is made at Y. In the tender equipment, Fig. 1, is shown a 
plain triple valve connected to the auxiliary reservoir, brake 
cylinder, and train line. Chamber C, as will be evident on 
studying the figure, is always charged with auxiliary pressure, 
and chamber B with train-line pressure, the piston 5 marking 
the line of separation between the two. The piston 5 may be 
moved up or down by increasing or decreasing the pressure in 
chamber B above or below that in chamber C. The packing 
ring 6 is made a good fit in the bushing, so that when the 
piston has moved down far enough to cover the groove m, air 
cannot readily pass by it in either direction. 



ACTION OF PARTS. 

50. The automatic portion of the mechanism of the plain 
triple consists of the slide valve 8, graduating valve 7, piston 5, 
and graduating stem 9. A sectional view of the slide valve 3, 
showing the graduating valve and ports, is given in view (6). 
The port w passes through the slide valve from one side to 
the other. When the graduating valve 7 is off its seat, 
auxiliary air can flow through port w past the valve and out 
at z, but when the valve is on its seat, no air can escape through 
port z. Besides ports iv and z, there is an exhaust cavity g in 
the face of the valve, as seen in view (a). The slide valve is 
surrounded by air at auxiliary pressure, which holds the valve 
to its seat. The spring 4 is provided to hold the valve to its- 
seat when there is no auxiliary pressure to perform this duty, 
thus preventing dirt from collecting on the valve seat and 
affecting the working of the triple. 

The piston 5 controls the movements of both the slide valve 
and the graduating valve. The slide valve fits loosely between 



30 THE AIR BRAKE. § 1 



shoulders on the piston stem, and, when the piston moves far 
enough, it carries the slide valve with it. The graduating 
valve 7 is connected to the stem of piston 5 by means of a 
small pin, shown in view (a), the place where it enters the pin 
and stem being shown by dotted lines; thus, the graduating 
valve is fixed with respect to the piston 5 and moves along with 
it. The length of the slide valve 3 is purposely made less than 
the distance between the shoulders on the piston stem, so that 
the piston in moving downwards will open, or, in moving 
upwards will close, the graduating valve 7, before it moves the 
slide valve 3. When the slide valve is in service position, the 
piston 5 can move up and down far enough (about T 3 g- inch) to 
operate the graduating valve without disturbing the slide valve. 
We thus see that the piston may move a limited distance with- 
out moving the slide valve; whereas, the graduating valve, 
being secured to the piston stem by the small pin referred to 
above, must move with the piston. 

51. The graduating stem 9 is held in position by the 
graduating spring 10. When a gradual, or service, reduction of 
train-line pressure is made, the pressure in chamber B is 
reduced below that in chamber C, and auxiliary pressure 
then moves piston 5 down until its knob j touches the gradu- 
ating stem 9, when the spring 10 prevents its moving any 
farther. When a sudden and heavy reduction of train-line 
pressure is made, as in emergencies, a sufficient difference of 
pressures is established in B and G to cause piston 5 to move 
down quickly and compress spring 10, the piston traveling the 
whole length of chamber B until it bottoms on the lower end. 

The graduating nut can be removed when it is desired to drain 
the triple or to examine the graduating stem and spring, w and 
z form one continuous port through the slide valve 3, as already 
explained in connection with view (6); this port is opened and 
closed by the graduating valve 7, and is called the service, or 
graduating, port. When the triple is in service position, air 
from the auxiliary reservoir flows through the slide valve by 
means of this port, thence into port / and on through port d 
into the brake cylinder. 



§ 1 THE AIR BRAKE. 31 



DUTIES OF THE TRIPLE VALYE. 

52. The triple valve has three duties to perform: (1) to 
charge the auxiliary; (2) to apply the brakes; and (3) to 
release the brakes. 

When an engine is coupled to a car, air from the main reser- 
voir flows back into the train pipe, thence through the branch 
pipe (as shown in Fig. 1), entering the triple at W. When the 
triple is ' ' cut in, ' ' the air can flow in at W, and on through 
ports a, b, c into chamber A, whence it passes into chamber B. 
If piston 5 were down, the air entering chamber B would force 
it up into release position, as shown in Fig. 7 (a). The feed 
groove m is now open, and air therefore feeds from chamber B 
past piston 5, through the grooves m and n into the slide-valve 
chamber C, which communicates through Fwith the auxiliary 
reservoir. The air continues to feed past piston 5 as long as 
train-pipe pressure in chamber B is greater than the auxiliary 
pressure in chamber C. The usual train-pipe pressure is 70 
pounds, and, when the auxiliary pressure has reached this 
amount, the pressures in chambers B and Care equal, and the 
auxiliary is said to be fully charged. The lower side of piston 5 
is generally referred to as the " train-pipe side," and the upper 
as the u auxiliary side," or the "slide-valve side. 



•> ) 



53. Charging Auxiliary Reservoir. — A modern triple 
valve should charge an auxiliary from zero up to 70 pounds 
in about 70 seconds, with a constant train-pipe pressure of 
70 pounds. With the triple in release position and the 
auxiliary charged, there will be 70 pounds in the train line, 
70 in the auxiliary, and no pressure at all in the brake cylinder, 
since the slide-valve cavity g connects the brake cylinder with 
the atmosphere, the communication being through the ports 
and passages r/, e, f, g, h, and k. 

54. Applying Brakes. — To apply brakes, it is necessary 
for a train-line reduction to be made. This may be made 
(1) in the usual way by the engineer, (2) by the use of the 
conductor's valve, or (3) by a break-in- two, a burst hose, or a 
heavy leak in the train line. 



32 THE AIR BRAKE. § 1 

If the engineer makes a reduction of 5 pounds in the train 
line, only 65 pounds will remain in chamber B, whereas at the 
beginning of the reduction, there will be 70 pounds in chamber 
C, or the auxiliary side of piston 5. This greater auxiliary 
pressure will force piston 5 downwards. While being forced 
down, it first closes the feed groove ra and unseats the gradu- 
ating valve 7, allowing auxiliary air to enter the slide valve 
at io and pass through to the end of port z. The air, however, 
cannot pass out of port z until the slide valve is moved to 
service position. By the time the graduating valve is unseated 
and the feed groove m closed, the shoulder lip on the upper end 
of the piston stem has engaged the slide valve and begun to 
move it down. As the slide valve moves down, the exhaust 
cavity g is closed to the ports /, e, and d leading to the brake 
cylinder. When the knob j touches the graduating stem P, 
the piston 5 is prevented from making any further downward 
movement. With the triple piston in this position, the service 
port z of the slide valve is directly in front of port /. This 
position of the valve is called the service position, and is shown in 
Fig. 7 (c). The graduating valve being off its seat, there is now 
an open communication between the auxiliary and the brake 
cylinder, and air flows from the auxiliary through the ports w 
and z in the slide valve, thence through the ports /, e, d, and 
out at Xinto the brake cylinder, where the pressure will force 
out the brake piston and set the brakes. Just so long as the 
auxiliary pressure is greater than that in the train pipe, so long 
will piston 5 be held down and the graduating valve remain 
unseated; but the auxiliary pressure gradually expands into 
the brake cylinder, until the pressure in chamber B is suffi- 
ciently greater than that in chamber C to overcome the small 
friction of the packing ring 6, and cause piston 5 to move 
upwards and seat the graduating valve, thereby closing port w. 
The pressure on the train-pipe side of the piston 5 still slightly 
exceeds that in the auxiliary, but not to such an extent as to 
overcome the additional friction encountered in moving the 
slide valve 3; the piston therefore stops as soon as the gradua- 
ting valve has been seated. This is called the lap position of 
the triple valve, in which position all ports are blanked. The 



§ 1 THE AIR BRAKE. 33 



brakes are now partially set; a further train- pipe reduction will 
be necessary to apply them any harder. 

If another 5-pound train-line reduction is made, the greater 
auxiliary pressure again forces the piston down, but in this case 
the slide valve was already in service position to begin with, 
and it is only necessary to move the piston down sufficiently to 
unseat the graduating valve. This is accomplished by the time 
the knob j touches the graduating stem 9; and once more, by 
means of the service part of the slide valve, communication is 
established between the auxiliary and the brake cylinder. The 
graduating valve is again seated automatically by the piston 5 
when the auxiliary pressure becomes a little less than that in 
the train pipe. 

After the slide valve has once been moved down, it remains 
in service position until the brakes are released. Each reduc- 
tion of train-pipe pressure causes the brake to set harder, and 
these reductions may be continued just as long as the pressure 
in the auxiliary is greater than that in the brake cylinder. 
When these pressures become equalized, the brake is fully set, 
and a further train- pipe reduction would be a waste of air. 
Ordinarily, a train-pipe reduction of about 20 pounds will cause 
a full application of the brakes. 

55. Releasing Brakes. — To release brakes, the engineer 
allows the air stored in the main reservoir to feed quickly into 
the train line. When the pressure on the train-line side of 
piston 5 is sufficient to overcome auxiliary pressure and the 
friction of the working parts, the piston is forced upwards to 
release position, carrying the graduating and slide valves with it. 
In this position, Fig. 7 («), the feed groove m is opened, and 
air from the train line feeds through m and n to recharge the 
auxiliary. At the same time, the pressure in the brake 
cylinder escapes through X and ports d, e, /, g, h, and k into 
the atmosphere. 

56. Emergency Application. — To apply brakes in an 
emergency, it is necessary to make a sudden and heavy train- 
pipe reduction. This sudden reduction causes piston 5 to move 
down very quickly and, compressing the graduating spring 10 y 



34 THE AIR BRAKE. § 1 

to traverse the full length of chamber B. In this position, a 
direct connection is established between the auxiliary and brake 
cylinder across the upper end of the slide valve 3, as shown in 
Fig. 7 (d). Auxiliary air passes direct into ports /, e i d 
and out into the brake cylinder at X, without having first to 
pass through the service parts of the slide valve. As only 
the large ports are used in emergency position, they allow the 
pressure in the auxiliary and brake cylinder to equalize more 
quickly than do the smaller ports used in the service position. 
With a plain triple, the brake sets more quickly in emergency, 
but not with greater force. 

To get the full emergency action of the brakes with plain 
triple valves, it is necessary to make a sudden reduction of 
about 20 pounds in train-line pressure. After an emergency 
application, the release of the brakes is accomplished in the 
same way as after a service application, already described. 



THE QUICK-ACTION TRIPLE VAIiVE. 



GENERAL REMARKS. 

57. The quick -action triple valve is automatic in its 
action and can be used on a train of which some of the cars are 
fitted with the plain triple, but it cannot be worked ' ' straight 
air," as can the plain triple, for when the triple valve is cut 
out, the communication from the train pipe to the brake cylin- 
der is also cut off. 

Fig, 1 shows the arrangement (on a passenger car) of the 
quick-action triple, auxiliary reservoir, brake cylinder, and 
connections. A T drain cup is inserted in the train line; a 
branch pipe extending from this T piece connects with the 
triple, as shown. 

In this branch pipe is a stop-cock 6, by means of which the 
brake on that particular car can be cut out or in, as desired, 
without interfering with the brakes on the rest of the train. 
When the handle of this cock stands at right angles, or cross- 
wise, to the branch pipe, the brake on that car is cut in, that is, 



§1 THE AIR BRAKE. 35 

it can be operated from the engine in the ordinary manner. 
When the handle is turned so as to be parallel to, or in line 
with, the pipe, the brake on that car is cut out, or is inoperative. 
Fig. 8 shows the triple connected to the brake cylinder, this 
illustration being on a larger scale than Fig. 1. The T piece 
just mentioned connects with the triple at W. The opening 
d of the triple valve communicates with the passage P in the 
cylinder head, through which passage air is conducted to and 
from the brake cylinder. The opening Y connects with a 
pipe 8 leading to the auxiliary reservoir, through which pipe 
the air is conducted between the auxiliary and the triple. 



DESCRIPTION. 

58. The parts of the quick- action triple "as numbered and 
lettered in Fig. 9 (a) are: 1, the drain cup; 2, the triple body; 
3, the slide valve; 4, the slide-valve spring; 5, the triple piston, 
and 6, its packing ring; 7, the graduating valve; 8, the emer- 
gency-valve piston; 9, the emergency- valve seat; 10, the emer- 
gency valve, also commonly known as the rubber-seated valve; 
11, the rubber seating; 12, the check-valve spring; IS, the check- 
valve case; 14-, the check-valve case gasket; 15, the check-valve; 
16, the train-pipe strainer, which keeps foreign substances from 
entering the triple; 17-18-27, a union joint; 20, the graduating- 
stem nut; 21, the graduating stem; 22, the graduating spring; 
and 23, a leather gasket. The branch pipe from the train pipe 
connects at W; the pipe to the brake cylinder connects at X; 
the auxiliary-reservoir connection is made at F; m and n are 
the feed grooves; and t is the port through which auxiliary 
pressure passes to the space above emergency piston 8 to 
operate the emergency valve 10. 

59. The quick-action triple contains two distinct sets of 
mechanism. One of these, consisting of the triple piston 5 
with stem, slide valve 3, and graduating valve 7 with stem 21 
and spring 22, is used in making service stops and in releasing 
brakes; it is often called the service 'part of the triple. The 
other set, consisting of the emergency piston 8, emergency 



36 THE AIR BRAKE. § 1 

valve 10, and train-pipe check -valve 15, is only brought into 
use in an emergency application of the brakes; * it is hence 
often called the emergency or quick-action part of the triple. 



SERVICE PART OF TRIPLE. 

60. Description. — The description and mode of action of 
the service part of the plain triple applies also to that of the 
quick-action triple, except in so far as the slide valves 3 differ 
somewhat in detail. As in the case of the plain triple, the stem 
of piston 5 engages with slide valve 3, and also operates the 
graduating valve 7. The service ports w and z in the valve 3 
are the same as in the plain triple, but this valve contains, in 
addition, an emergency port s; also, the valve is longer, and one 
of its edges or corners is cut away, as shown at q in Fig. 9 (b). 
This latter view represents the valve as transparent, so as to 
show the ports better, and it is turned upwards so as to show 
the exhaust cavity g in its face; w Sid z are the service ports con- 
trolled by the graduating valve 7; s is the emergency port, the 
end s f of which is smaller than port z\ q is generally referred 
to as the removed corner of the valve. Cavity g, and ports 
w, z, and s are shown also in Fig. 9 (a). The port/, with pas- 
sages ee' and d, leads to the brake cylinder; port t, as already 
mentioned, leads to the space above emergency piston 8; and 
exhaust ports h and k lead to the atmosphere. The ports 
/, t, h, and k are also shown in view (c), which is a view of the 
valve seat 21f. 

When the slide valve is in emergency position, the removed 
corner q allows auxiliary air to pass down through port t and 
force piston 8 downwards. This unseats emergency valve 10, 
and opens communication between the train pipe and the brake 
cylinder; the check-valve 15 is then raised by train-pipe pres- 
sure and allows train-pipe air to pass to the brake cylinder. 

61. Rubber-Seated Valve. — The duty of the emer- 
gency, or rubber-seated, valve is to prevent the train-pipe 
air from passing into the brake cylinder through chamber J 
and port d, except when required to do so in emergency appli- 
cations. Were it not for this valve 10, the brakes would apply 




Service Pos 




Service Pos< 



1 THE AIR BRAKE. 37 



as soon as air was turned into the train pipe, and, the triple 
exhaust port k being open, there would be a constant blow 
through to the atmosphere. 

62. Train-Pipe Check.— The train-pipe check 15 pre- 
vents the brake- cylinder pressure from flowing back into the 
train pipe, in the event of a hose bursting or the train line 
breaking, or at any time when the train- pipe pressure is less 
than the brake-cylinder pressure. If a hose were to burst, 
all the air would leave the train pipe, and the brakes on the 
entire train would set in full. If the train-pipe check 15 were 
not in the triple, there would be nothing to prevent air passing 
from the cylinder to the train pipe and out to the atmosphere, 
in case the train parted or a hose burst. This would release 
that brake. 

Spring 12 holds valve 10 to its seat when there is no air 
pressure present to perform this duty, and, also, when the 
pressures in chambers y and I become equalized after an 
emergency application of the brake. It performs the same duty 
for train-pipe check 15. 

63. Train-pipe air entering the triple at W feeds through 
the passage a b and port c, and on through the feed grooves m 
and n into chamber C, thence through Y into the auxiliary. If, 
when air enters the triple, there is no pressure on top of the 
train-pipe check 15, the air underneath will raise it from its seat 
against the force of the spring 12 and fill chamber y, forcing the 
rubber-seated valve 10 more firmly on its seat. When the pres- 
sure in the chamber y and the force exerted by the spring 12 
are together slightly greater than the train-pipe pressure 
underneath the check-valve 15, this valve is forced to its 
seat and thenceforth plays no further part unless an emergency 
application is made. 

64. Release Position. — The slide valve of the quick- 
action triple is shown in release position in Fig. 9 (a). In 
this position, any air that may be in the brake cylinder can 
pass through passages d and e' e, port /, cavity g of the slide 
valve, and the port h, out through exhaust port k to the 
atmosphere. Port k is also shown in view (c), as is also the 



38 THE AIR BRAKE. §1 

port/ leading through the passage ee' to the brake cylinder, 
and port t leading to the top of the emergency piston 8. 

65. Service Position. — When a service application of 
the brakes is made (by gradually reducing train-pipe pressure), 
the triple piston 5 moves out until the knob j touches the 
graduating stem 21, view (d), after which any further move- 
ment is prevented. The service port w and port z of the slide 
valve now connect with the brake cylinder by way of port / 
and passages ee' and d. As the graduating valve 7 opens 
before the slide valve moves forward, air now passes from the 
auxiliary reservoir through ports w, z,f, and passages ee', d, to 
the brake cylinder until auxiliary pressure is reduced just a 
trifle below train-pipe pressure, when the graduating valve 7 is 
closed. During succeeding reductions, the graduating valve 
simply opens and closes without moving the slide valve, as 
already explained in describing the action of the plain triple. 



EMERGENCY PART OF TRIPLE. 

66, When, in cases of danger, etc., a sudden reduction of 
train-pipe pressure is made, what is termed the emergency 
part of the triple valve is called into play; the triple piston 5 
moves out quickly, the graduating spring 22 is compressed, and 
the triple piston travels the full length of chamber B. This, the 
emergency position of the triple, is shown in view (e). In this 
position, port s in the slide valve connects with port /in its seat, 
and auxiliary pressure can pass through the ports s,f, and pas- 
sages e e', d, out at X into the brake cylinder. The removed 
corner q of the slide valve, view (6), has shortly before this 
reached a position directly above port t, view (e), thus allowing 
auxiliary air to pass down through port t on to the top of the 
emergency piston 8, forcing it downwards. This downward 
movement unseats the emergency valve 10, and allows the 
air in chamber y above the emergency check 15 to escape. 
Train-line pressure beneath this check-valve now forces the 
latter from its seat, and air from the train pipe passes up by it, 
on through chamber y and the unseated emergency valve 10, 
into chamber 7, and out at X to the brake cylinder. The 



§1 THE AIR BRAKE. 39 

emergency valve remains unseated until the pressures in cham- 
bers y and i" are nearly equalized, when the spring 12 forces the 
emergency valve and check- valve to their seats. 

The position of the removed corner q on the slide valve is 
such that, as the valve moves forward to emergency position, 
it connects port t of the valve seat with auxiliary pressure a 
short time before port s connects with port /. The emergency 
valves therefore open before port s, and, consequently, train- 
pipe air — which passes like a flash through the large openings 
of the emergency valves — is first to equalize with the brake 
cylinder, the equalizing pressure being about 20 pounds when 
check- valve 15 closes. As soon as port s connects with port /, 
auxiliary pressure discharges into, and equalizes with, the brake 
cylinder; but, since the cylinder already contains about 20 
pounds pressure, they equalize at about 60 pounds pressure 
instead of at 50 pounds, as in a service application. 

The emergency port s of the slide valve is made smaller at s f 
than the service port z, to retard the flow of air somewhat 
from the auxiliary reservoir to the brake cylinder during an 
emergency application of the brakes, so as to allow as much air 
as possible to enter the brake cylinder from the train pipe, and 
thus increase the final brake-cylinder pressure. 

67. Plain and Quick- Action Triples Compared. 

Comparing the plain and the quick-action triples, it will be seen 
that they both work exactly the same in a service application, 
but that the quick-action triple sets the brake both quicker and 
harder in emergency. The quick- action triple also sets the 
brake harder in emergency than in service application, owing to 
the emergency valve, piston, and check-valve operating so as to 
allow train-pipe pressure to enter the brake cylinder and aid 
the auxiliary pressure in applying the brake. 

The plain triple sets the brake quicker in emergency than it 
did in service, owing to the use of larger ports; but the brake 
does not set any harder, since it simply has auxiliary pressure 
to use in applying the brakes in either service or emergency. 

When a quick-action triple goes into emergency position, a 
sudden train-pipe reduction is made near it when the emergency 



40 THE AIR BRAKE. 



valve opens. This sudden reduction starts the next quick- 
action triple, and that starts the next, and so on throughout 
the train. If from any defect one triple goes into quick action, 
all will follow. 

Ordinarily, a gradual train-pipe reduction of about 20 pounds 
will cause a plain or a quick-action triple valve to equalize the 
pressures between the auxiliary and brake cylinders at about 
50 pounds. In emergency, with a quick-action triple, the pres- 
sures are equalized at about 60 pounds, while with the plain, 
the same pressure is obtained in the cylinder in emergency 
as in a full-service application, namely, 50 pounds. With 
quick-action triples, a sudden train-pipe reduction of 10 or 12 
pounds will produce a full emergency action of the brakes; 
while, with a plain triple, a reduction of about 20 pounds is 
necessary. The reason for this is that a 12- pound reduction 
will cause the emergency valves of the first triples to open and 
produce a further train-pipe reduction. Train-pipe pressure is 
not affected in this way when a plain triple goes into emergency, 
and, therefore, while a sudden 12-pound reduction would force 
the triple to emergency position, it would not stay there, as it 
would be forced back to lap or perhaps to release, as soon as 
auxiliary pressure had reduced the 12 pounds. It is necessary, 
therefore, to reduce train-pipe pressure below that at which the 
auxiliary and brake cylinders equalize, to obtain a full emer- 
gency application with plain triples. 



FREIGHT AND PASSENGER EQUIPMENTS. 

68. Equipments Compared. — An illustration of the 
freight-car equipment now used is given in Fig. 10. It 
consists of auxiliary reservoir 10, brake cylinder 2, and triple 
valve 18. This equipment has to be made very compact on 
account of the limited space for it on freight cars; but, while it 
appears to be different from that used on passenger cars, shown 
in Fig. 1, yet it is exactly the same in principle and operation. 

In the passenger-car equipment, Fig. 8, there is a pipe 8 
leading from chamber Y of the triple valve to the auxiliary 



§1 THE AIR BRAKE. 41 



reservoir, whereas, in the case of the freight-car equipment, 
Fig. 10, the air passing from the train pipe through the triple 
goes direct to the auxiliary. 

In the freight equipment, pipe b connects the triple valve 18 
with the brake cylinder, while in the passenger equipment, 
the triple is fastened directly to the cylinder. When the brake 
is released in a freight equipment, air from the brake cylinder 
flows through pipe b and out through the triple exhaust to 
the atmosphere. 

In the passenger equipment (Fig. 8), the piston rod is 
fastened to the crosshead 7, and the brake levers, also con- 
nected to the crosshead 7, are controlled by the cylinder piston, 
the levers being moved every time the piston moves. In a 
freight equipment (Fig. 10), this is not so, as a push rod, 
bottoming on the piston, is inserted in the sleeve 3. The outer 
end of the push rod (not shown in figure) is connected to the 
brake levers, and, when the hand-brakes are applied, the push 
rod may be drawn out without moving the piston. When the 
air brake is applied, piston 3 is forced out, carrying the push 
rod with it. 

There are practically no points of difference in the freight 
and passenger equipments other than those already described, 
and a description of the parts in the one will apply equally to 
those of the other. The various parts of the triple valve have 
already been described and the mode of working explained. 

69. Description. — The auxiliary reservoir 10 (Fig. 
10) is a storage reservoir. The air stored there is for use in the 
cylinder #, and its use is confined entirely to the car on which 
it is placed. 

The release valve 17, or bleed cock, as it is sometimes called, 
is for reducing the auxiliary pressure. If the brake on any 
particular car should ' ' stick, ' ' it can be released by opening 
the bleed cock of the auxiliary on that car until air begins to 
exhaust from the triple valve, when the bleed cock should 
immediately be closed. Bleeding the auxiliary reduces the 
pressure there below that in the train pipe, which consequently 
forces the triple piston to release position and releases the brake. 



42 



THE AIR BRAKE. 



§1 




The brake cylinder can 
be oiled by means of the 
oil plug 16; there is a 
similar plug on the other 
side of the cylinder. Either 
may be used for the above 
purpose. 

The piston 3 is operated 
by the air pressure in ap- 
plying the brakes. In the 
top of the brake cylinder 
will be noticed a small 
groove a. This is known 
as the leakage groove, 
and its purpose is to allow 
any air that may be in the 
brake cylinder (either hav- 
ing leaked into the brake 
cylinder, or passed in from 
the triple valve during a 
very light application of 
the brake, as when coup- 
ling up hose and making 
up trains) to pass by pis- 
ton S and out to the 
atmosphere through the 
open end of the cylinder. 
The groove is placed in 
the top of the cylinder 
(in which position it is 
least likely to become 
clogged with dirt), and is 
of such a length that the 
brake piston must move 
out about 3 inches before 
the groove is covered. 
Leakage grooves are now 
cut in the side of brake 



§ 1 THE AIR BRAKE. 43 



cylinders instead of at the top. Leakage grooves are found in 
the brake cylinders of freight and passenger cars, and also on 
most tenders, but not in driver-brake cylinders, until recently. 
9 is the release spring; when, in applying the brakes, air enters 
the cylinder and forces piston 3 out, the release spring is com- 
pressed; in releasing the brake, air leaves the cylinder and the 
release spring forces piston 3 back to release position, as shown 
in Fig. 10. 4- is the front cylinder head; it acts as a guide 
for the sleeve 3. 

The cup leather packing 7 is to keep the air that enters the 
cylinder from passing by the piston; it takes the place of 
the ordinary iron packing rings used in steam cylinders. 6 is 
the follower plate, which holds the leather packing in place. 
8 is the expander ring, which forces out the leather against the 
walls of the brake cylinder, and so prevents air from passing 
the piston. As the air enters the cylinder, it strikes the flanges 
of the, leather, forcing them against the walls of the cylinder, 
and forming an air-tight joint. 



TRAIN-PIPE COUPLINGS. 

70. In Fig. 11 (a) is shown an air-brake hose H with the 
nipple iYand coupling C attached; they are fastened to the hose 
by means of the clamps c, c. (b) is an enlarged view of the 
coupling C shown in (a) ; this is a device for coupling together 
the hose on two adjacent cars, (d) is an angle cock, one of 
which is attached to each end of the train pipe on each car, as 
seen in Fig. 1. Connection is made between hose and angle 
cock by means of the hose nipple N, shown in (a), which is 
screwed into the angle cock at i, the end 6 of the cock itself 
being screwed on to the train pipe. 2 is a plug valve operated 
by the handle 4- 3 is the liner, or bushing, in which the plug 2 
works; it constitutes the valve body. As the valve now stands, 
air can pass through it. To stop the flow of air, the handle 
must be placed at right angles to the position here shown. The 
spring 5 holds the plug tight to its seat. In views (a) and 



44 



THE AIR BRAKE. 



(6), 2 is a rubber gasket, by means of which a tight joint 
is made when the couplings are united between two cars, (c) is 
called a coupling hook. The coupling C when not in use 




Fig. 11. 



is hung in the coupling hook, instead of allowing the hose 
to hang down and collect dirt, snow, and cinders, which would 
gradually work into the triples and impair their action. 



§1 



THE AIR BRAKE. 



45 



RETAINING VALYE. 

71. Its Duty. — The retaining valve, shown in Fig. 12, 
is used on freight cars in all sections of the country, and on 
passenger cars, engines, and tenders in mountainous districts. 

It is located at the end of the car, in such a position as to be 
within easy reach of the trainmen when the train is in motion, 
and is connected by a pipe at Xwith the exhaust port of the 
triple valve. 

Its purpose is to retain a pressure of 15 pounds in the brake 
cylinder, in order to have sufficient braking power to keep the 




Fig. 12. 

speed of a train from increasing too rapidly while the engineer 
is recharging the train after a release on a grade, preparatory to 
another application of the brakes. 

The retainer cap 3 acts as a guide, and keeps the weighted 
valve Jf from falling out. It also retards the flow of air from the 
brake cylinder by forcing it to pass out of the small opening at d. 
The valve 4- is of such a weight that it requires a pressure of 



46 



THE AIR BRAKE. 



§1 



15 pounds per square inch in port b' in order to raise it. The 
body of the retaining valve is shown at 2\ 6 is a plug valve 
operated by the handle 5. 



72. Operation. — When the retaining valve is cut out, the 
handle 5 points straight downwards, as in view (6). If the 
triples are released with the handle 5 in that position, air from 
the brake cylinder will pass through the exhaust port of the 
triple, through the pipe connecting the triple valve with the 
retainer at X, and on through ports b, a, and e to the atmos- 
phere. If, when the brakes are released, the handle 5 is in the 
position shown in view (a), the air coming from the brake 
cylinder and entering the retainer at X will pass through ports 
b and b' and so come in contact with the weighted valve If. 

Any pressure above 15 pounds 
per square inch will raise 
valve If. and pass out to the 
atmosphere through port d. 
When t h e brake-cylinder 
pressure is reduced to 15 
pounds, valve If reseats itself 
and holds the remaining 
pressure in the cylinder. The 
diameter of port d at the 
smallest part is yg- inch. This 
port is made small so as to 
further retard the passage of 
air from the brake cylinder to 
the atmosphere. The conse- 
quence of this is that pressure 
accumulates in the cap 3\ 
which acts in concert with 
the weight of valve If to close 
the valve for a few seconds 
at frequent intervals until the 
15 pounds; consequently, the brake- 
It takes about 20 




Fig. 13. 



pressure is reduced to 

cylinder pressure reduces rather slowly 

seconds for a brake-cylinder pressure of 50 pounds, with average 



1 THE AIR BRAKE. 47 



piston travel, to reduce through the retainer to 15 pounds, 
using a modern retainer with the small port d. 

In an earlier form of retaining valve, there were two J-inch 
holes located similarly to port d, These large ports allowed 
the brake-cylinder pressure to reduce so rapidly that the valve 
was not sufficiently effective on heavy grades. 

Fig. 13 shows the improved retaining valve, which differs 
from that shown in Fig. 12 in that its plug cock 6 is held 
always on its seat by the spring 8. Also, the weighted valve 
seats on a bushing 9; 7 is the cap for the cock 6; the arrange- 
ment of ports in the cock is the same as in Fig. 12. The view 
of this valve is as seen from the front when on the car, whereas 
Fig. 12 is a side view. The action of this valve is the same as 
the other; when the handle 5 is turned down, as in the figure, 
the valve is cut out; when it stands out straight (i. e. hori- 
zontally), it is cut in, and will retain 15 pounds in the brake 
cylinder. The port d is in this valve also, but is not shown 
in this view, owing to the manner in which the section has 
been taken. 

The retaining valve has nothing to. do with applying the 
brakes; it simply retains a certain amount of pressure in the 
brake cylinder when the triple valve goes to release position. 



ENGINEER'S D-8 BRAKE VALVE. 

73. The engineer's brake valve is that part of the air- 
brake equipment by means of which the engineer can control the 
action of the brakes. The two kinds of brake valves now in use 
are the D-8 and the D-5, E-6, or F-6, the latter three terms 
denoting one and the same valve, the letter and number being 
changed as each new catalogue is issued. The D-8 is gradually 
being supplanted by the F-6, but there are still a large number 
of the former in use. 

74. Description. — The D-8 brake valve is shown in 
Fig. 14, views (a) and (b) being cross-sections, and (c) a plan 
view with the rotary valve and handle removed so as to show 
the rotary seat. View (d) shows the face of the rotary valve 
and the ports and cavities in it. View (e) is a horizontal section 



48 



THE AIR BRAKE. 



1 



through the excess-pressure valve 21 in view (&).■ In view (e) 
is shown the passage /' leading from the feed-port/ to chamber 
r on one side of the excess-pressure valve, and the passage xf\ 
which leads from the other side of the excess-pressure valve to 
the direct-application-and-supply port I. 

Fig. 14 (a) and (6) and also Fig. 15 show the rotary valve 
13 in release position, with cavity b of the rotary seat con- 
necting port a of the rotary with cavity c, which latter connects 
with port I. 

In view (d), which shows the face of rotary valve 13, q is a 




Fig. 15. 



pin that fits into a hole in the rotary seat; it acts as a guide 
for the rotary. The supply port a and also port j pass entirely 
through the rotary, while c is a cavity in the face of the rotary, 
but not extending through it; p is a small groove in the face 
of the rotary. When the valve is in service position, this groove 
connects port e with port h, view (c), and thus establishes a 
connection between the equalizing reservoir and the atmos- 
phere; w, in view (d), is a bridge separating port a from 
cavity c. 



§ 1 THE AIR BRAKE. 49 

The direct-application-and-supply port I leads to the train 
pipe through the passage I' ', as shown in view (a), the train 
pipe being connected at Y. The direct- application- and-exhaust 
port k, view (c), leads direct to the atmosphere. 

The preliminary- exhaust port h leads down and out to the 
atmosphere, as shown in view (6). In this view, also, is seen 
how the preliminary-exhaust port e leads through the rotary- 
valve seat into chamber D, the cavity or space above the equali- 
zing piston 17 which is connected directly with the equalizing 
reservoir through port s and the pipe connection T. 

The supply port b, views (a) and (c), is simply a cavity 
in the rotary seat, and is only used in full-release position to 
establish communication between port a and cavity c of the 
rotary. Fig. 15 shows the rotary valve in release position, 
with the cavity b establishing communication between port a 
and cavity c, the passage of the air from port a through 
cavity 6, into cavity c, and from thence to port I and the train 
pipe being indicated by arrows. 

The equalizing port g, Fig. 14 (c), leads into chamber D. 
In running and full-release positions, this port serves to establish 
a connection between both sides of the equalizing piston 17, 
that is, between chamber D (or equalizing-reservoir pressure) 
and train pipe. Pipe connection is made between z on the 
pump governor, Figs. 3 and 4, and V in Fig. 14 (a) and (c); 
the pump governor, therefore, is operated by train-pipe pres- 
sure when used with this valve. 



EQUALIZING RESERVOIR. 

75. The small equalizing reservoir or brake- valve reser- 
voir, sometimes called the little drum, Fig. 1, is generally placed 
under the cab foot-board. A pipe leads from this small drum to 
the engineer's valve, where it connects at T Fig. 14, and thence 
through port s with chamber D. The equalizing reservoir 
serves to increase the capacity of chamber D without enlarging 
the engineer's valve. Were chamber D of small capacity, it 
would be impossible to make a gradual service application of 
the brakes, for the reason that a gradual reduction of pressure 






50 THE AIR BRAKE. § 1 



could not be made in chamber D; the least opening from this 
chamber would cause a great reduction of pressure and conse- 
quently would set the brakes harder than desired. 

The black gauge hand is connected at W, and it therefore indi- 
cates chamber D and equalizing-reservoir pressure. The red 
gauge hand is connected at R and so indicates main-reservoir 
pressure, this reservoir being piped to the brake valve at X. 

The equalizing piston 17 separates chamber D from the 
train pipe pressure, chamber D pressure always acting to hold it 
down, and train-pipe pressure to force it up. As long as these 
two pressures remain equal, the piston remains stationary, but 
if the equalizing-reservoir pressure is reduced below that in the 
train pipe, the piston will be raised by train-pipe pressure, which 
will then escape to the atmosphere through port m, train-pipe 
exhaust valve E, and port n n' , views (a) and (b). As soon as 
the train-pipe pressure under piston 17 is reduced below that in 
chamber D, the piston is forced down by the pressure above it, 
and closes the train- pipe exhaust valve E. 

It is essential that a thorough knowledge be acquired of the 
ports and cavities of the brake valve, and their connections in 
the different positions of the rotary, in order to obtain a clear 
conception of the various brake-valve operations. 



BRAKE- VALVE POSITIONS. 

76. There are five positions in which the brake valve may 
be used, namely: (1) release, (2) running, (3) lap, (4) service, 
and (5) emergency. 

Release Position. — This position, Fig. 14 (a) and (6), is 
used in releasing the brakes, and in charging the equalizing 
reservoir, train line, and auxiliary, reservoirs. 

Running Position. — This is the position used while the 
brakes are off, as when running along the road. It is also 
sometimes improperly used in releasing brakes on a very 
short train. 

Lap Position. — In this position, the rotary valve closes and 
separates all the brake-valve ports. The brake- valve handle is 
carried on lap position between reductions in a service stop. 



§1 THE AIR BRAKE. 51 

Service Position. — This is the one used in making a 
gradual application of the brakes, such as at stations, water 
cranes, slow-ups, and the like. 

Emergency Position. — This is used when it is desired 
to stop a train in the shortest possible time, as in cases of 
imminent danger. 

OPERATION OF D-8 BRAKE VALVE. 

77. It must be remembered that main- reservoir pressure is 
always free to enter the brake valve at X, and, unless otherwise 
stated, we shall consider 70 pounds as standard train-pipe, and 
90 pounds as standard main-reservoir, pressure. 

78. Release Position. — To release brakes, the brake- 
valve handle is placed in full-release position, namely, that 
shown in Fig. 14 (a) and (6). This brings the supply port a 
of the rotary valve 13 in such a position over cavity b in its 
seat that the partition w between port a and cavity c of the 
rotary is directly over the center of cavity b in the seat (see 
Fig. 15). The supply port a is thus directly connected with 
cavity c by means of cavity 6, and air passes from port a 
into cavity c as shown by the arrows in Fig. 15, cavity c being 
then in direct connection with port I. A direct connection is 
thus had with the main- reservoir pressure (which is always on 
top of the rotary valve) by way of the supply port a down into 
cavity b of the rotary seat, up into cavity c of the rotary, and 
then down through the direct-application- and- supply port I 
and the passage V y Fig. 14, into the train pipe at F, raising the 
pressure in the train pipe and charging the auxiliaries through 
the triples. At the same time that air is passing through 
cavity c into the train pipe, it also passes into chamber D 
through port g, which port is exposed to cavity c, and in this 
way the pressures are kept equal both above and below the 
equalizing piston 17. 

In full-release position, port j is directly over port e leading to 
chamber D, and this furnishes another port connection between 
the main reservoir and this chamber, views (6) and (d). 
Thus, when the rotary is in full release, it is seen that there 



52 THE AIR BRAKE. § 1 

are two small port connections between the main reservoir and 
chamber D, and one large one between the main reservoir and 
train pipe. 

The pump is stopped by the governor when the train-pipe 
pressure has reached 70 pounds, so that if the rotary is left in 
full- release position, 70 pounds is all that will be obtained in 
the main reservoir, train pipe, and equalizing reservoir, since 
a direct connection is established between these three places 
in this position. 

The brake- valve handle, therefore, should be moved to run- 
ning position just before 70 pounds has been reached, in order 
to have the proper excess pressure. 

79. Running Position. — In this position, the partition 
w in the rotary valve has been moved around so as to break the 
connection between port a and cavity c. Air may now pass 
from port a into cavity b, but cannot get out. In this position, 
port j of the rotary is directly over the feed-port /, and port e 
is blanked. With the brake valve in this position, the main- 
reservoir pressure reaches the train pipe by passing down 
through port j of the rotary into port /and passage/', and so on 
into chamber r, where it moves the excess-pressure valve 21 
from its seat and passes on through passage xj" into port I 
leading to the train line. Cavity c still establishes communi- 
cation between port I and equalizing port g, so that, as air enters 
the train pipe, it is also free to pass up into cavity c of the 
rotary and down through port g into chamber D. A direct 
connection is thus obtained in running position between the 
train pipe and chamber D, the pressures above and below the 
equalizing piston 17 are equal, and the black gauge hand, which 
usually indicates chamber D pressure only, now shows train- 
pipe pressure also, due to the above direct connection. 

In running position, air can only pass from the main reservoir 
by the excess-pressure valve 21 into the train pipe when 
there is 20 pounds more pressure in the main reservoir than 
there is in the train pipe. This is because the excess-pressure 
spring 20, which holds the excess-pressure valve 21 to its seat, 
has a resistance equivalent to this excess of 20 pounds, which 



§ 1 THE AIR BRAKE 53 

resistance must be overcome before valve 21 can be raised from 
its seat. If the pump is started with the brake valve in run- 
ning position, the red gauge hand will show 20 pounds pressure 
before the black hand moves at all. The hands will continue 
to rise 20 pounds apart until 90 pounds is obtained in the main 
reservoir, and 70 in the train-pipe, when the pump will stop, 
since the governor is worked by train-pipe pressure and is 
adjusted to 70 pounds. The difference between the main-reser- 
voir and train-pipe pressures is called the excess pressure. 

80. X^ap Position. — With the valve handle in this posi- 
tion, all ports are closed. Port j of the rotary, views (b) and 
(d), has been moved around past port /, and the rotary now 
covers port g. The main reservoir, chamber D, and train pipe 
are entirely separated from one another, and the black hand 
now indicates only chamber D or equalizing-reservoir pressure, 
as there is now no port connection between the upper and lower 
sides of the equalizing piston 17. 

81. Service Position. — When in this position, the valve 
handle will have been moved so that groove p of the rotary 13, 
view (d), connects the preliminary- exhaust port e, views (6) 
and (c), with port h leading to atmosphere. The engineer 
leaves the rotary in service position until the black hand 
shows that the desired reduction of chamber D pressure above 
piston 17 has been made, when the rotary is again moved to 
lap position. In service position, the only port connection 
through the rotary is between chamber D and the atmosphere, 
through ports e, p, and h. Chamber D pressure, on top of the 
equalizing piston 17, now being reduced below train-pipe 
pressure underneath it, this piston rises, opening the train- 
pipe exhaust port E, and permitting train-pipe air to escape 
through ports m and nn' to the atmosphere at the train-pipe 
exhaust 25. Train-pipe air continues to escape at the train- 
pipe exhaust until the pressure below piston 17 is a trifle less 
than that in chamber D above it, at. which time the piston is 
forced down, closing the train-pipe exhaust valve E. If the 
rotary is again placed in service position, the events just 
described will again occur, the amount of train-pipe reduction 



54 THE AIR BRAKE. §1 

corresponding to the reduction of equalizing-reservoir pressure. 
When the engineer makes a service application of the brakes, 
he simply makes a reduction of chamber D pressure, and 
then piston 17 automatically reduces the train-pipe pressure; 
while piston 17 is reducing the train-pipe pressure, the triple- 
valve pistons are automatically reducing the pressure in the 
auxiliaries by allowing it to escape into the brake cylinders. 

82. Emergency Position. — In this position, the cavity c 
of the rotary valve is so placed that it connects the direct- 
application-and-supply port I, which leads to the train pipe, 
with the direct-application-and-exhaust port k, leading to the 
atmosphere. This port k, the cavity c, and the port I, all being 
large, cause a large opening to be made between the train pipe 
and atmosphere, and, consequently, a sudden heavy train-pipe 
reduction is the result. This sudden reduction causes the 
triples near the engine to assume emergency position. It was 
seen in the study of the quick-action triple that when one 
quick-action triple went into emergency position, a sudden 
reduction of train-pipe pressure near it was made through the 
quick-action part of the triple; this started the next one, and 
so on to the end of the train, each triple helping to keep this 
sudden reduction traveling quickly backwards throughout the 
train. In the service application of the brake, all train- pipe 
reductions escape to the atmosphere through the train-pipe 
exhaust, while in emergenc}^, a sudden reduction is made to 
start the first quick-action triples into emergency, and these 
triples make sudden reductions of train- pipe pressure; but, 
instead of wasting the air by passing it to the atmosphere, 
they put it into the brake cylinders, where it is used to increase 
the braking power. 

ENGINEER'S 3>5, E-6, OR F-6 BRAKE VALYE. 

83. The F-6 brake valve is illustrated in Fig. 16, wherein 
(a) and (b) are cross-sectional views, while (c) is a plan view, 
with the top part of the valve body and the rotary valve 13 
removed, so as to show the ports and cavities in the rotary- 
valve seat S. In (d) is shown a plan view of the under side, 



THE AIR BRAKE. 55 



or face, of the rotary IS, showing the ports and cavities in it. 
View (e) represents a section of the valve taken through the 
passage f'f", to show the passages to and from the feed-valve 
attachment. Comparing Fig. 16 (d) with the plan of the D-8 
rotary valve shown in Fig. 14 (d), it will be seen that cavity c 
is in about the same position in each case, but that the two 
differ slightly in form. 

84. The excess-pressure valve 21, of the D-8 valve, is 
replaced in the F-6 valve by the feed-valve attachment 33, 
(6) and (c). The excess-pressure valve in the D-8 maintains a 
predetermined difference of pressure between the main reservoir 
and the train pipe; the feed-valve attachment can be regulated 
to give any desired train-pipe pressure (as high as that in the 
main reservoir if desired), regardless of what the main-reservoir 
pressure is. The pump governor used with the F-6 valve 
controls the pump, and, consequently, the excess pressure. 

The air connection z of the pump governor (Figs. 3 and 4) 
is connected by a pipe at R, Fig. 16, and the governor, there- 
fore, is operated by main-reservoir pressure. 

The equalizing reservoir is connected at T, the black gauge 
hand at W, and the red one at R. The pipe connections to the 
train line and the main reservoir are the same in this as in the 
D-8 valve. The various operating positions of the brake valve 
handle (release, running, lap, service, and emergency') are also the 
same as for the D-8 valve, as shown in Fig. 14 (c). 



OPERATION OF F-6 BRAKE VALVE. 

85. The feed- valve attachment, shown in Fig. 16 (b), 
consists of a spring box 69, within which is contained a regula- 
ting spring 68, which exerts an upward pressure on the feed- 
valve piston 74- above it, and within the feed-valve body is a 
supply valve 68, the lower stem of which is of such a length that 
it rests on the upper stem of the feed- valve piston. When this 
piston is up in its normal position, it holds the valve 6S from its 
seat against the resistance of the spring 64, which tends to hold 
the valve down. When the brake valve is in running position, 

LofC 



56 THE AIR BRAKE. §1 

chamber u, above the supply valve 63, is in connection with 
main-reservoir pressure through the passage /"/', port / in the 
rotary seat, and port j in the rotary valve. Chamber B, j ust above 
piston 74, is in direct communication with the train line at all 
times through port and passage i, and direct- application- and- 
supply port I, view (e). Chamber B is therefore always filled 
with train-pipe pressure, which exerts a downward pressure on 
piston 74, while chamber u is always filled with main-reservoir 
pressure. The downward pressure of the air in chamber B on 
piston 74 is resisted by the spring 68, which is adjusted to 
resist a downward pressure of 70 pounds per square inch. Just 
so long as the train-pipe pressure in chamber B is less than 
70 pounds, the spring 68 will hold piston 74 up sufficiently to 
keep the supply valve 63 unseated, and main-reservoir pressure 
will flow by valve 63 into chamber B, and on into the train 
pipe, view (e). When the pressure in the train pipe and in 
chamber B reaches 70 pounds, the piston 74 is forced down, 
compressing the spring 68. As piston 74 descends, the supply 
valve 63 is forced to its seat by the spring 64, and no more 
air can pass from the main reservoir into the train pipe 
through the feed- valve attachment (or train-pipe governor, 
as it is sometimes called), until a reduction of train-pipe 
pressure has occurred. 

If leaks reduce the train-pipe pressure below 70 pounds, the 
spring 68 raises piston 74 an d supply valve 63, and allows 
main-reservoir pressure to restore the loss due to leakage, after 
which the supply valve 63 is again closed. The tension of the 
spring 68 is regulated by means of the regulating nut and screw 
70. Screwing up increases the tension of spring, and, conse- 
quently, the train-pipe pressure, and unscrewing reduces 
train-pipe pressure. In view (6), the feed-valve attachment 
is shown in section; a small portion of the body is further 
broken away so as to show the port i by which the air, after 
passing from u through the feed-valve into B, makes its way 
along the passage shown into port I; this passage runs along 
behind the passage /"/'> exactly on the same level with it, 
so that it cannot be seen in view (6); its position, however, 
is shown in view (e). 



§ 1 THE AIR BRAKE. 57 



86. Release Position. — When the brake valve is in this 
position, (a) and (6), the supply port a of the rotary stands 
directly over cavity b of the rotary seat, and portj of the rotary 
stands directly over the preliminary- exhaust port e, view (6). 
Main-reservoir pressure is free to pass into port a of the rotary, 
and down into cavity b of the rotary seat. The bridge w, 
between cavity c and port a of the rotary, view (d), now stands 
across the middle of cavity b, so that the air entering cavity b 
from port a passes under this bridge and up into cavity c, as 
shown in Fig. 15. The air passes from cavity c into the supply 
port I and out into the train line at Y. Train-pipe pressure 
increasing, the triple pistons are forced to release position and 
the auxiliaries are charged. While the air is passing through 
cavity c to port I, it is free to pass down through the equalizing 
port g into chamber D, and thence out to the equalizing 
reservoir through port s. During the time air is feeding into 
the chamber D through port g, main-reservoir air is feeding 
through port j of the rotary and the preliminary-exhaust port e 
of its seat into the chamber D. In release position, one large 
port leads from the main reservoir to the train pipe, and two 
small ports lead to the equalizing reservoir (through chamber D). 
In view (d) is seen a very small port r, called the engineer's 
warning port, drilled through the rotary valve in such a posi- 
tion that, when the latter is in full release, this warning port 
is directly over the exhaust port k in the rotary seat, view (c). 
Main-reservoir air on top of the rotary blows through this 
small warning port into the emergency exhaust, and the sound 
of escaping air is heard by the engineer. This sound is to warn 
him that he must not leave his valve in full-release position too 
long, for the following reasons: With this valve, the pump is 
not stopped until 90 pounds pressure is obtained in the main 
reservoir, as main-reservoir pressure operates the pump gov- 
ernor, which is adjusted to 90 pounds. Now, there is a direct 
connection between the main reservoir and train pipe in full- 
release position, and if the rotary is left there, 90 pounds pres- 
sure will be obtained in both the main reservoir and train pipe. 
This high pressure, getting into the auxiliaries, would be likely 
to slide wheels when the brakes were applied, and there would 



58 THE AIR BRAKE. 



also be a lack of excess pressure for releasing brakes. Besides 
this, if the valve were now placed in running position, the feed- 
valve attachment would be held closed until train-pipe pressure 
was reduced to 70 pounds, and, consequently, train-pipe leaks 
would tend to cause the brakes to ' ' creep on ' ' until both train- 
pipe and auxiliary pressures were reduced to 70 pounds, when 
the feed-valve would begin operating again, and supply the air 
lost through these leaks. 

87. Running Position. — In this position, port j of the 
rotary is in communication with port /of the rotary seat, and 
air from the main reservoir passes down through ports j, /, 
through the passage/'/", and on through the feed-valve attach- 
ment and into the train pipe by way of passage i and port I, 
as explained in the description of the feed-valve attachment. 
The air continues to flow thus until the train-pipe pressure 
reaches 70 pounds, when the feed-valve attachment closes. 
As air passes through the feed- valve attachment through port i 
and on into port I and the train pipe, some of it passes up 
into cavity c in the rotary, and down through port g into 
chamber D. A connection is thus obtained between the train 
pipe and chamber D, that is, between both sides of the equal- 
izing piston 17. The black gauge hand is piped to the 
equalizing- reservoir connection at T, and, as there is in run- 
ning position a port connection between the train pipe and 
chamber D, through the cavity c in the rotary and port g, the 
black hand must in this position indicate both chamber D and 
train-pipe pressures. The same movement that changes the 
rotary 13 from full release to running position, closes the warn- 
ing port r and moves the bridge w of the rotary, so that it 
prevents the passage of air from cavity b of the rotary seat into 
cavity c of the rotary. The feed- valve attachment keeps the 
train-pipe pressure at 70 pounds, and the pump governor stops 
the pump when main-reservoir pressure has reached 90 pounds, 
so that, when everything is fully charged and the valve is in 
running position, the black hand should register 70 pounds 
and the red hand 90. 



§ 1 THE AIR BRAKE. 59 

88. l-ap Position. — In this position, the rotary has been 
moved around so as to close all connections. Port j is closed 
to port/; the equalizing port g is covered so that it is shut off 
from cavity c, and connection between the top and bottom of 
the equalizing piston 17 is cut off. 

89. Service Position. — In this position, the rotary has 
been moved so that groove p in the face of the rotary valve, 
view (d), connects the preliminary- exhaust port e in the rotary 
seat with the port h % which leads into the direct-application- 
and-exhaust port k (called also the emergency-exhaust 
port). A direct connection is thus established between cham- 
ber D and the atmosphere, and air from chamber D can pass 
through port e, groove p, and ports h and k to the atmosphere. 
The reduction of the pressure in chamber D causes the equal- 
izing piston to rise and open the train-pipe exhaust valve E, as 
already described in the operation of the D-8 valve. 

90. Emergency Position. — In this position, the rotary 
has been moved around so that cavity c connects port I 
(leading to the train pipe) with the emergency- exhaust port k 
(leading to the atmosphere). The opening of these large ports 
causes a sudden train-pipe reduction, which give an emergency 
application of the brakes, as already described in the case 
of the D-8 valve. 



The Air Brake 

(PART 2.) 



DEFECTS AND THEIK REMEDIES. 



THE PUMP GOVERNOR. 

1. Its Importance. — The air pump is the life of the 
air-brake system, since its duty is to supply air, without which 
the brakes cannot be operated. Anything that renders the pump 
inoperative, therefore, makes the air-brake system useless. 

The pump governor is a throttle valve whose duty is to 
automatically control the air pump; hence, any disorder in the 
governor will affect the working of the pump and make the 
brake system less reliable and effective, or it may render 
the system entirely useless until cut out. 



IMPROVED GOVERNOR. 

2. Causes of Failure to Operate. — If the governor 
does not operate the pump properly, and cannot be made to do 
so by adjusting the tension of the spring 4-1, the trouble may be 
due to any of the following causes: (1) Leaky pin valve; 
(2) steam valve held open by solid matter on its seat; (3) relief 
port stopped up; (4) drip pipe frozen or stopped up; (5) pin 
valve held on its seat by the spring box; and (6) governor 
piston stuck in bushing. 

1. Leaky Pin Valve. — This may be due to the pin valve 6, 
Fig. 3,* not seating properly; or to solid matter, such as dirt, 



*A11 figure numbers used in this Section refer to the illustrations in 
The Air Brake, Part 1. 

§2 



THE AIR BRAKE. §2 



gum, or scale, holding the valve from its seat. A leaky pin 
valve allows air at main-reservoir pressure (or train- pipe, as the 
case may be) to pass from chamber a past valve b and through 
passage d into chamber e above the governor piston 28. If the 
air leaks past the valve faster than it can escape through the 
relief port c, pressure will accumulate in chamber e and force 
the governor piston downwards, so as to wholly or partially close 
the steam valve 26. If the steam valve is closed, the pump 
will, of course, stop; if only partial^ closed, the steam supply 
will be throttled and the pump will work more slowly than 
usual. A slight leak past the pin valve will simply make the 
governor less prompt in starting the pump after the pin valve 
closes, and it will be indicated by a constant discharge of air 
from the relief port c. 

The pin valve may be removed for cleaning by unscrewing 
the spring box from the diaphragm body. 

2. Steam Valve Held Open. — If the steam valve 26 is held 
from its seat by dirt or solid matter, the pump will continue to 
work until sufficient pressure is accumulated in the main reser- 
voir to stop it. In this case, although the pin valve b may 
work properly, and open when a main-reservoir pressure of 
90 pounds is obtained, yet the dirt on the seat of the steam 
valve will prevent the steam valve from closing, and the pump, 
consequently, will continue to work, although at a slower 
speed than usual. A leaky steam valve, also, will keep the 
pump moving slowly. 

3. Relief Port Stopped Up. — It will be remembered that the 
duty of the relief port c is to allow the air to escape from 
chamber e when the pin valve b closes, so that the pump will 
start promptly. If port c is stopped up, this means of escape 
is cut off, and the air will have to leak past the packing ring 29 
and out of the drip pipe. The rapidity with which it will do 
this depends on the fit of the packing ring; if this fit is at all 
snug, the governor steam valve 26 may not open until some 
little time after the pin valve closes. In this case, therefore, it 
is possible for leaks to reduce main-reservoir pressure several 
pounds before the pump begins to work again. 



§2 THE AIR BRAKE. 3 

4. Drip Pipe Stopped Up. — If the drip pipe is frozen or 
stopped up and the stem of the steam valve 26 is worn, steam 
will feed up into the chamber under the governor piston and 
prevent the piston from being forced downwards to close the 
steam valve 26. The pump, therefore, will continue to work 
until sufficient pressure is accumulated to stop it. A worn 
steam- valve stem will be indicated by steam escaping from the 
drip pipe — if the latter is not stopped up. Even though the 
stem does not leak sufficiently to prevent the steam valve from 
being closed, the pump will continue to work, for air will leak 
down past the piston packing-ring as soon as the pin valve 
opens, and accumulate under the piston. This soon raises the 
piston, and thus opens the steam valve. The pump then starts, 
and continues to work until stopped by the pressure in the 
main reservoir. 

5. Pin Valve Held on Its Seat by Spring Box. — If the pin 
valve is too long, or the edge of the diaphragm body so reduced 
that the pin valve is held on its seat when the spring box is 
screwed down tight, the governor will not work at all. To test 
for this defect, slack off on the spring box and see if the 
governor will then operate. 

6. Governor Piston Stuck in Bushing. — If the bushing in 
which the governor piston works becomes badly worn, the 
piston is liable to stick at the lower end of its stroke, and 
the pump will not start. A light tap on the governor or on the 
steam pipe near it is usually sufficient, however, to start it 
operating again. 

OLD-STYLE GOVERNOR. 

3. Defects of This Governor. — All that has been said 
about the causes of trouble with the improved governor is 
equally applicable to the old-style governor, with the excep- 
tion of that part which refers to the relief port c of the former 
kind. 

Besides the sources of trouble already enumerated, the old- 
style governor has another one: The diaphragm 19, Fig. 4, is not 
sufficiently supported, and, as a consequence, main-reservoir 



THE AIR BRAKE. §2 



pressure sometimes raises the diaphragm until it "buckles." 
When this occurs, the regulating spring 18 seems to lose all con- 
trol of the diaphragm, and the pin valve 17 is liable to open 
and stop the pump at almost any pressure — sometimes stop- 
ping it before standard pressure is obtained, and at other times 
not until standard pressure has been exceeded. A governor 
in this condition is worse than useless, and should be cut 
out of service until a new diaphragm can be substituted. In 
fact, whenever the governor becomes disabled, and, for any 
reason, cannot be repaired on the road, it should be cut out of 
service, and the pump operated by hand — by means of the 
pump throttle. 

CUTTING OUT A GOVERNOR. 

4. In case a governor becomes disabled, it may be cut out 
by placing a blind gasket in the air pipe leading to it, as, for 
instance, in the union at z, or by plugging the small opening 
that leads into chamber a. In either case, pressure will be 
excluded from chamber a, and, consequently, the steam valve 
will remain open, thus providing for the steam a free passage 
through the governor. 

PUMPS. 



PACKING THE PUMP. 

5. The life and efficiency of an air-brake pump depend, 
to a great extent, on the care it receives. In packing such a 
pump, any substance that will harden, such as asbestos, should 
not be used. Also, care should be exercised not to screw the 
packing gland nuts too tight, as the rubbing friction between 
the piston rod and packing, when the latter is pressed too hard 
against the former, may produce sufficient heat to burn the 
packing out, and cause unnecessary trouble on the road. If 
the gland nuts can be screwed up sufficiently by hand to pre- 
vent a blow, no wrench should be used. A blow should be 
stopped as soon after it occurs as possible, as the steam, in 



§2 THE AIR BRAKE. 5 

escaping, tends to cut a channel through the packing along the 
piston rod, and thus spoil it. 

A swab saturated with oil should always be used on the 
piston rod. This not only serves to keep the rod and packing, 
but also the air cylinder, in good condition, as some of its oil 
works down into the latter and helps to lubricate it. 



OILING THE PUMP. 

6. Steam Cylinder. — A sufficient quantity of good oil 
should be used in the steam cylinder to keep the parts well 
lubricated and prevent groaning. The quantity of oil neces- 
sary will depend on the kind of oil used, and also on the pump 
itself, as some pumps require more than others. If the pump 
groans constantly, and the pump exhaust or the drip pipes 
show that considerable water is working through the steam 
cylinder, its dry pipes should be examined for leaks that might 
allow water to reach the pump and wash out the oil. 

7. Air Cylinder. — The quantity of oil to be used in the 
air cylinder depends to a great extent on the pump, but in any 
case it should be used very sparingly. The amount should 
only be sufficient to keep the packing rings free, and prevent 
the cylinder walls from cutting. If too much is used, a gummy 
deposit is formed in the air cylinder and air passages, and on 
the air valves, which tends to cause heating; also, oil works 
back into the brake valve and triples, and causes them to work 
poorly; 32° West Virginia well oil is considered best for use in 
the air cylinder. The oil may be fed to the cylinder by means 
of a swab on the piston rod, or through the air-cylinder oil 
cups, but it should never be fed through the air inlets, as it will 
close the air passages, gum up the valves, reduce their lift, and 
sooner or later result in overheating. Animal or vegetable oils 
should not be used in the air cylinder, as they "gum" very 
readily; also, mineral oils that have a low flashing point, as, for 
instance, kerosene, should not be used in a hot cylinder, as they 
generate an explosive gas that ignites at a comparatively low 
temperature, and may, therefore, cause trouble. 



THE AIR BRAKE. §2 



CLEANING OUT THE PUMP. 

8. Occasionally, the air cylinder of an air pump gets a fit 
of "groaning." When this occurs, the lower air-cylinder head 
should be removed, the piston pushed up to the top end of the 
cylinder, and the cylinder thoroughly cleaned by means of a 
piece of waste saturated with kerosene. The cylinder should 
then be wiped out thoroughly with clean waste, and oiled lightly 
with a good grade of mineral oil or vaseline, after which the 
head may be replaced. 

If the air passages of a pump become gummed up, they may 
be cleaned out by working a potash solution through the air 
cylinder. To do this, disconnect the air-discharge pipe at the 
main reservoir, and make provision for catching the solution as 
it is discharged through this outlet. Run the pump very 
slowly, and allow the potash to be drawn in through the air- 
inlet ports, and thus worked through the pump. Pass the same 
solution through four or five times, or until the passages are 
clean. Sufficient clean hot water must then be worked through 
the pump to thoroughly cleanse it of all potash, since, if any is 
allowed to remain, it will gradually work back into the brake 
system, destroy the gaskets, and work mischief in general. If a 
potash solution cannot be had, use hot soapy water, or even 
clear hot water alone. 

RUNNING THE PUMP. 

9. Starting. — When first starting the pump, the drain 
cocks Ifl, Fig. 5; or 105 and 106, Fig. 6, should be opened, and 
left so until the pump is thoroughly warm; it should be 
started slowly to allow the water of condensation to escape 
gradually, and to prevent pounding. No provision is made in 
the steam end of an air pump for bringing the piston to rest 
easily by means of cushioning, since, when the pump is working 
against pressure, the air in the air cylinder acts as a cushion. 
When the pump is first started, however, there is little or no 
pressure in the main reservoir, and, consequently, there is 
nothing to prevent the pistons from striking the cylinder heads 



§2 THE AIR BRAKE. 



violently if the pump throttle is opened very wide. For this 
reason, the pump should be run slowly until sufficient pressure 
is accumulated to cushion the pistons — about 25 or 30 pounds. 
After the pump is warm, the drain cocks should be closed, and 
the throttle may be opened wide enough to run the pump at 
the required speed. The air-pump lubricator should be turned 
on as soon as the pump is started, since, by oiling the cylinder 
well at the start, less oil will be necessary afterwards to keep it 
working smoothly. If a pump groans badly in the top end, the 
reversing piston probably needs oil; in this case, close the pump 
throttle, remove the reversing-chamber cap, and pour in a small 
quantity of good valve oil. 

10. Speed of Pump. — To obtain the best results from a 
pump, it should not be run at a slower speed than from 45 to 
60 strokes a minute. The speed may be increased as occasion 
demands, but "racing" should be avoided, as it causes over- 
heating. 

If a pump is run too slowly, some of the air, being com- 
pressed, will pass by the packing rings, and expand and fill the 
other end of the cylinder, and thus less fresh air will be drawn 
in through the suction valve at each stroke; in consequence of 
this, the pump heats up and its efficiency is greatly reduced. 
When the pump is run at its proper speed, however, the air has 
less time in which to pass by the piston packing-rings; conse- 
quently, the pump heats less and its efficiency is greater. 



LIFT OF AIR VALVES. 

11. The lift of the receiving air- valves in the 8-inch pump 
should be % inch, and that of the discharge valves, -fa inch. 
The lift of both the receiving and the discharge valves of 
the 9J-inch pump should be -$% inch. All the air valves in the 
9^-inch pump are of the same size; in the 8-inch pump, the 
receiving valves are smaller than the discharge valves, and, 
hence, must have a higher lift to accommodate the passage 
of the air. 



8 THE AIR BRAKE. § 2 

WORKING TEMPERATURE OF PUMP. 

12. Conditions Affecting- the Temperature. — The 
normal temperature of a pump depends on: (1) the 
quantity of air it compresses; (2) the rate at which the air is 
compressed; (3) the pressure against which the pump works; 
and (4) the temperature of the air before compression. 

1. Quantity of Air Compressed. — The greater the quantity of 
air compressed in a given time, the more continuously, or else 
the faster, the pump will have to work in order to compress it; 
hence, the greater the normal temperature of the pump. 

2. Rate of Compression. — Experiment shows that the faster 
the air is compressed, the higher will be its final temperature; 
also, the faster the pump is run, the less time there is for the 
radiation of heat between strokes. Hence, since more heat is 
generated, and less heat radiated at each stroke of the pump, it 
is evident that the temperature of the pump must increase with 
its speed. 

3. Resisting Pressure. — More power is employed when 
working against a higher than when working against a lower 
pressure; therefore, heat is generated at a greater rate. Also, 
experiment shows that the final temperature of air under com- 
pression increases with the pressure. 

4. Temperature of Air Before Compression. — Experiment 
shows that air at 0° F. will have a final temperature of about 
360° F. when compressed to 90 pounds pressure, while air at 
100° F. will have a temperature of about 530° F. , the speed of 
the compressor being the same in both cases. 



EXCESSIVE HEATING OF PUMP. 

13. Causes of Overheating. — The overheating of a 

pump may be due to one of the following causes: (1) Continu- 
ous high speed; (2) excessive pressure to work against; (3) air- 
piston rings badly worn; (4) air cylinder leaking; (5) main 
reservoir leaking back into air cylinder; (6) air passages in 
pump or air-discharge pipe partially stopped up; (7) air valves 
stuck shut; or (8) too small a main reservoir. 



THE AIR BRAKE. 



1, 2. Continuous High Speed, or Excessive Pressure. — It has 
already been shown (see preceding article) how either of these 
causes will result in excessive heating. 

3. Leahy Piston Packing-Rings. — This defect will cause a 
pump to overheat more quickly and to a higher degree than 
any of the other causes; consequently, the air- piston packing 
rings should receive frequent attention. 

When the packing rings are badly worn, air can pass by them 
in either direction; consequently, less air is taken into the 
cylinder and less forced into the main reservoir at each stroke 
than if the rings were tight. As the piston moves forwards, it 
compresses, and, therefore, raises the temperature of the air in 
front of it; some of this air then escapes past the piston, and 
raises the temperature of the incoming air considerably, before it 
is compressed. This results in a still higher final temperature of 
the air when compressed, and that portion which in its turn 
escapes past the piston is at a higher temperature, and, hence, 
heats the incoming air to a higher degree than in the previous 
stroke. At each stroke of the piston, the air that leaks by is 
hotter than in the previous stroke, and raises the temperature 
of the incoming air still more, until, finally, the pump is badly 
overheated. 

There is also another effect due to leaky packing rings: 
Since the pump neither takes in nor discharges as much air 
as it would if in normal condition, it follows that a greater 
number of strokes will have to be made to pnmp up main- 
reservoir pressure; consequently, the pump will have to work 
faster or for a longer time than usual, either of which contin- 
gencies will help to overheat it. 

To test for worn piston packing-rings run the pump at a 
speed of about 45 strokes per minute, and place the hand over 
the air-inlet ports. If on both the up and down strokes of the 
pump, air is drawn in during the first part of the stroke only, 
the suction ceasing during the latter part, it indicates that the 
packing rings need renewing. The reason why the suction ceases 
before the end of the stroke is as follows: As the piston moves 
forwards at the beginning of its stroke, a vacuum is created, and 
air is drawn into the cylinder behind it, but, as the piston 



10 THE AIR BRAKE. §2 

continues to advance, the air in front is gradually compressed 
until, finally, it is forced past the packing rings in sufficient 
quantities to destroy the vacuum and thus the suction. 

4. Leakage From the Air Cylinder. — Any such leakage, either 
through a leaky or broken receiving valve, or a blow in the 
piston-rod packing, reduces the amount of air pumped per 
stroke, and the pump must either be run faster or for a longer 
time to compress a given amount. 

A leaky receiving valve is indicated by air blowing back 
through the valve as the piston moves towards it. Also, it 
causes the piston to take a quicker stroke when traveling in 
that direction. To test for a leaky receiving valve in an 8-inch 
pump, hold the hand over the air- inlet ports; air will be forced 
out as the piston moves towards the leaky valve. 

In the 9^-inch air pump (Fig. 6), the air for both ends of 
the air cylinder enters through the inlet W; consequently, air 
will be drawn in on both the up and the down strokes. Sup- 
pose the lower receiving valve 86' to leak; then, as the piston 
moves towards the valve, it compresses the air in that end of the 
cylinder and forces some through the leak. This air, instead 
of being forced out of the inlet port W, passes up through the 
passage F, past the upper receiving valve 86, and through 
port m, into the other end of the cylinder; consequently, less 
air is drawn in through the inlet port, to fill this end of the 
cylinder. [See view (c).] To test for a leaky receiving valve 
in the 9J-inch pump, therefore, run the pump slowly and 
place the hand over the inlet port; the suction will be less on 
the stroke towards the leaky valve. Also, the stroke towards 
the leaky valve will be quicker than the one from it. 

5. Back Leakage From Main Reservoir. — This may be due to 
a broken discharge valve, to a defective valve seat, or to the 
valve being held from its seat by dirt or gum. Any of these 
causes will allow air to be compressed into the main reservoir, 
but, when the pump is reversed, the air will flow back through 
the defective valve and hold the receiving valve for that end of 
the cylinder to its seat; consequently, there will be no suction 
for that end of the cylinder. Also, the strokes of the pump will 



THE AIR BRAKE. 11 



be uneven, the one toivards the defective valve being the slowest. 
If the upper discharge valve leaks, it will be indicated by a con- 
tinuous discharge of air from the air-cylinder oil cup, if it is 
opened. If the lower discharge valve leaks, it will be indicated 
by a continuous discharge of air from the plug hole in lower 
cylinder head. 

6. Air Passages or Discharge Pipe Stopped Up. — Occasionally 
the air passages or the air-discharge pipe become partly closed 
with gum and dirt. This increases the back pressure on the 
pump. It has also another effect: when the air-inlet passages 
are choked, the pump does not draw in as much air at a stroke 
as it should; while a choked discharge pipe increases the 
leakage past the piston rings, and more power is therefore 
necessary to force air into the main reservoir. These effects 
will cause the pump to run slower than usual, and heat up. 

If the air valves have too little lift, the effect will be the same 
as though the air passages were choked. If only one of the 
valves has too little lift, the strokes of the pump will be 
uneven — the faster stroke being towards the defective valve, if a 
receiving valve, or from it, if a discharge valve. 

7. Air Valves Stuck Shut. — If it is a receiving valve, there 
will be no suction as the piston moves away from it; the strokes 
of the pump will be uneven, the one towards the defective 
valve being the faster. The pump will probably pound on the 
fast stroke, and it will also become heated. The reason why 
the strokes are uneven is that the vacuum, formed in the end of 
the cylinder in which the stuck valve is, works against the steam 
pressure on the stroke away from the stuck valve, and with it on 
the return stroke. If both receiving valves are stuck, there will 
be no suction on either stroke of the pump; the pump will 
pound and heat, and the red hand of the gauge will not move 
forwards. The strokes, however, will be even, but the pump 
will run faster than usual. If the air-inlet ports become frozen 
or stopped up, the effect will be the same as though both 
receiving valves were stuck shut. 

If a discharge valve is stuck shut, the strokes of the pump 
will be uneven, the slow stroke being towards the defective valve; 



12 THE AIR BRAKE. §2 

there will be no suction as the piston moves away from it, and 
the pump will heat. The reason why the strokes are uneven, 
is as follows: The cylinder is full of air as the piston starts 
towards the stuck valve, and, since the valve is closed and the 
air cannot escape, it is compressed and offers a steadily increas- 
ing resistance to the movement of the piston. The stroke away 
from the stuck valve is assisted by this compressed air, which 
acts like a compressed spring to force the piston along. As the 
force exerted by the air acts against the steam pressure in the 
first instance, and with it in the second, it is evident that one 
stroke will be faster than the other. 

Should both discharge valves stick, the pump will run faster 
than usual and heat badly, and there will be no suction on 
either stroke, the piston simply churning back and forth in the 
cylinder. In this case, also, the red hand of the gauge will not 
move forwards. If the discharge pipe is frozen or stopped up, 
it will have the same effect as if both discharge valves were 
stuck shut. When the strokes of the pump are uneven, the 
pump is generally referred to as being "lame." 

8. Main Reservoir Too Small. — The use of a small main 
reservoir in heavy freight service is very often the cause of 
the pump overheating, since it does not hold sufficient air to 
release the brakes and recharge the auxiliaries promptly, and 
the pump, consequently, must be worked faster when the 
brakes are released. A pump is not as efficient when hot 
as when cold, since air, on entering a hot cylinder, expands, 
and, consequently, less is required to fill it at atmospheric 
pressure; hence, the pump, when hot, must make a greater 
number of strokes, to do a given amount of work, than 
when cold. 



POUNDING IN PUMP. 

14. Usual Causes. — Pounding in an air pump may be 
due to any one of a number of causes. It may be due to water 
in the cylinder; to the pump being loose on the brackets that 
hold it, or the brackets being loose on the boiler; to the main 
piston striking against cylinder heads; to the nuts 58 of the 



§2 THE AIR BRAKE. 13 

8-inch pump, or corresponding nuts on the 9J-inch pump, 
working loose and striking the air-cylinder head; or to the 
air valves pounding on their seats, due to too much lift. 
In addition to the foregoing, the 8- inch pump may pound 
if the main valve strikes the stop-pin, or if the reversing piston 
strikes either the reversing-chamber cap, or the bottom of the 
reversing chamber itself. 

Clearance in Pump. — The clearance in an air pump is pur- 
posely made as small as possible, the air as it is compressed in 
the air cylinder being relied on to act as a cushion for the 
pistons, to prevent their striking the cylinder heads. Packing 
rings that are badly worn, or receiving valves that are stuck, 
broken, or leaky, will destroy this cushioning effect of the air, 
and hence will allow the pump to pound. Also, the reversing 
plate, or the button on the reversing rod, may be so worn that 
the pump is not reversed in time to prevent the piston striking 
the heads and causing a pound. 

Parts Too Long. — If either the stop-pin 50, the main valve 
7", or the stem of the reversing piston 28 is too long, it may 
make the main valve strike the stop-pin and cause a pound. 
The stop-pin is intended to prevent the main valve dropping 
down far enough (when steam is shut off) to allow the piston 
packing-rings to expand below the bushings and prevent the 
main valve rising. 

The combined length of the main-valve spindle, reversing- 
piston stem, and stop-pin should be such that, when the 
reversing piston is bottomed on its bushing and the valve 
spindle is tight up against it, there will be about -g- 5 ¥ inch space 
between the bottom of the main-valve spindle and the stop-pin. 
When this space is provided, there will be no pounding of the 
main valve. 

Reversing Piston Striking. — Before the reversing piston 28 can 
commence its upward stroke, the reversing valve 16 must close 
the steam port a in the upper steam-cylinder head and connect 
port b with the exhaust passage c. Therefore, as soon as the 
reversing piston, in moving upwards, closes the exhaust port b, 
the steam caught above it is compressed and forms a cushion 



14 THE AIR BRAKE. §2 

that brings the reversing piston and main valve to rest with- 
out pounding. 

The small ports near the bottom of the reversing-piston 
bushing 22 connect the lower end of this bushing with the 
exhaust passage /. As soon as the reversing piston 28, on its 
downward stroke, closes the lower one of these ports, it com- 
presses the exhaust steam caught below it, and thus provides a 
cushion for this stroke. If, however, the packing rings are 
badly worn, the steam, instead of being compressed, will leak 
by them, thus reducing or totally destroying the cushion, and 
allowing the reversing piston to strike the cap, or the bottom of 
the bushing, as the case may be. 



9^-INCH PUMP BLOWING. 

15. Usual Causes. — A blow in the steam end of the 
9|-inch pump may be due to: (1) a leak past the seat of 
the reversing valve 72; (2) the reversing rod worn, and loose 
in the reversing- valve chamber cap; (3) a leak past slide valve 
83; (4) worn packing rings in either piston of the main valve 
76; (5) worn packing rings in steam piston 65; or, (6) the 
gasket between the top cylinder head and the cylinder not 
making a tight joint. 

1. Reversing Valve Leaking. — If the reversing valve 72 leaked 
through into port /, Fig. 6 (6), there would be a blow, since 
steam from the reversing- valve bushing would pass through 
ports / and /' and exhaust port d out into the atmosphere. 
This probably would be a light blow, however, and it would be 
continuous, since port / connects directly with the exhaust 
port d. 

2. Worn Reversing Rod. — If the top of the reversing rod 
were worn so as to be loose in the cap nut 7Jf, steam could pass 
by the stem into the cap nut, and thence through port x and the 
passage that runs down alongside the reversing-valve bushing, 
into the top of the steam cylinder 61. On the up stroke of the 
piston, this end of the cylinder is connected with the exhaust; 
consequently, the leak described would cause a constant, though 
light, blow during the up stroke. 



§2 THE AIR BRAKE. 15 



S, Slide Valve Leaking. — If there were a leak past the slide 
valve 83, it would cause a constant blow through the exhaust 
port d while the pump was working. 

4. Main -Valve Rings Blowing. — Worn packing rings in 
piston 79 of the main piston valve 76 will also cause a constant 
blow at the exhaust during the time the pump is working, since 
chamber E is always connected with the atmosphere through the 
passage t' t, view (d). Chamber B (to the right of piston 77} 
is connected with the exhaust only during the up stroke of the 
pump; hence, worn packing rings on piston 77 will cause a 
blow on the up stroke only. 

5. Steam-Piston Rings Blowing. — Worn packing rings in 
steam piston 65 will cause a constant blow at the exhaust while 
the pump is working, since one end of the cylinder is always 
full of steam while the other end is connected to the exhaust, 
and steam can readily pass the packing rings. A leak past the 
steam-piston packing rings will generally produce the strongest 
blow of all. 

6. Leaky Gasket. — The gasket between the top cylinder head 
and the cylinder may permit steam to escape into the exhaust 
passage d! d" , or into the steam passage b f b" . In the first 
case it will cause a blow on 'the down stroke only, since the 
upper end of the cylinder is connected to the steam supply on 
that stroke only. In the second case, the steam will escape 
from the upper end of the cylinder through the passage b\ 
port 6, and out at the exhaust d to the atmosphere, on the 
down stroke. On the up stroke, steam will escape from the 
passage &', through the leak in the gasket, into the upper end of 
the cylinder, and thence out through the exhaust. In the 
second case, therefore, the leak will cause a constant blow. 



8-INCH PUMP BLOTTING. 

16. Usual Causes. — A blow will be produced in the steam 
end of the 8-inch air pump: (1) if the reversing valve 16 is 
worn so that steam can escape into the exhaust passage; (2) if 
the end of the reversing rod in the cap nut 20 is worn and 
allows steam to escape past it; (3) if the packing rings or the 



16 THE AIR BRAKE. §2 

pistons of the main valve 7, or of the reversing piston 23, are 
worn or broken; or (4) if the packing rings of the steam 
piston 10 are worn or broken. 

1. Reversing Valve Leaking. — A constant blow will occur if 
the reversing valve is so worn that steam escapes through the 
ports c, //, and g to the exhaust. 

2. Worn Reversing Rod. — If the end of the reversing rod 17 
in the cap nut 20 is worn, steam can escape by it and pass 
through the passage x into the upper end of the steam cylinder 3. 
This will cause a blow on the up stroke, since the upper 
end of the cylinder is open to the exhaust on that stroke. 

3. Main-Valve Rings Blowing. — If the packing rings in 
either of the pistons of the main valve are worn or broken, 
there will be a constant blow at the exhaust, since ports //and 
/ /' are always in connection with port g, which leads to the 
exhaust at Y. 

Reversing- Piston Rings Blowing. — If the packing rings in the 
reversing piston 23 leak, there will be a blow on the up stroke, 
the steam escaping past the packing rings 24-, thence through 
the small ports at the bottom of the reversing chamber, and 
on through the passages // and g to the exhaust at Y. The 
blow will occur only during the up stroke, since there is no 
steam in chamber d above the reversing piston during the down 
stroke. 

4. Steam-Piston Rings Blowing. — If the packing rings of 
the steam piston allow steam to escape past them, a constant 
blow will be produced, as explained in connection with the 
9J-inch pump. 

9|-INCH PUMP STOPS. 

IT. Usual Causes. — It should be remembered that certain 
defects in the pump governor will cause the pump to stop. To 
determine whether or not the governor is at fault, open the 
drain cock 106, Fig. 6; if steam escapes freely, the trouble is 
not in the governor. 

But little trouble has been experienced with the 9 J-inch 
pump stopping, about the only thing that will stop one of these 



§2 THE AIR BRAKE. 17 



pumps being a bent or broken reversing rod 71, or a bad leak 
between the steam passage b f b" and the upper end of the steam 
cylinder, due to a defect in the copper gasket between the head 
and the cylinder. The former prevents the pump reversing, 
while the latter allows live steam to enter the exhaust end of 
the cylinder at each stroke, which increases the back pressure 
against which the pump is working; consequently, if the pump 
is not in good condition and is working against a high main- 
reservoir pressure, it may stop. 

18. A Former Cause of Trouble. — Trouble was expe- 
rienced with some of the first 9-^-inch pumps, owing to the 
fact that the large piston 77 of. the main valve could pass 
beyond and close the port g" in the bushing 75, view (c?). 
This prevented the admission of steam to chamber B, as a 
result of which the main valve was unable to take its stroke to 
the left, and the pump would stop. This was remedied by 
cutting a groove on the inside of the bushing, from port g" to 
the end; and, further, a steam space was provided behind the 
piston by turning the head down -^ inch, except a portion at 
the center; thus, the steam can always pass freely to the back 
of the piston, which insures the valve making its stroke to the 
left, view (a). The tendency of the pump to stop at the top 
of its up stroke was thus overcome. 



8-INCH PUMP STOPS. 

19. locating the Cause. — Since, in the 8-inch pump, 
there is no drain cock similar to 106, Fig. 6, a different test 
must be made to determine whether the governor is reponsible 
for the pump stopping. 

If the governor is operated by train-pipe pressure, close the 
cut-out cock 5 in the train pipe just below the brake valve, 
Fig. 1, and place the brake-valve handle in service position; 
this gradually reduces the pressure in the chamber a of the 
governor, Fig. 3; hence, the force exerted by the regulating 
spring Ifl to close the pin valve b gradually increases. If the 



18 THE AIR BRAKE. §2 

pump does not start by the time the train-pipe pressure is fully 
discharged, the probability is that the pump, and not the 
governor, is at fault. Of course, if the governor has a relief 
port c, a constant blow from this port will indicate that the 
fault is in the governor. 

If the governor is operated by main-reservoir pressure, close 
the cut-out cock as before, "lap" the brake valve, and then 
disconnect the air pipe from the governor at the union z. If 
the pump then starts, it indicates that the fault lies with 
the governor. 

Another method that may be used when the governor is 
connected to either main-reservoir or train-pipe pressure, is to 
disconnect the steam-supply pipe to the pump at the union X, 
and note whether steam is supplied freely. 

20. Usual Causes of Pump Stopping. — If the trouble 
is in the pump, it may be that: (1) the stop-pin 50 is broken or 
is too short; (2) the main-valve or reversing-piston packing 
rings are broken; (3) the reversing rod is bent or broken; 
(4) the reversing plate is loose or worn out; (5) the main 
piston-rod nuts are loose or broken; or, (6) the pump is very 
dry from lack of lubrication. 

1. Defective Stop-Pin. — A stop-pin that is broken or is too 
short will allow the main valve to drop down sufficiently for 
the packing rings to expand below the bushings 25 and 26. 
This will prevent the valve from taking an up stroke, and the 
motion of the pump cannot be reversed. In this case, steam 
will be admitted below piston 10 through the lower steam 
ports, and the pump will always stop on the upper end of 
the stroke. 

Sometimes, in a case of this kind, the pump can be started by 
giving it steam and tapping lightly near the bushings. If this 
does not start it, and circumstances are such that the upper 
steam -cylinder head can be removed, it may be possible to 
forcibly raise the valve, although there is danger of breaking 
the packing rings or spiders in the effort. 

If the valve cannot be raised in this way, the only remedy 
will be to remove the cylinder from the centerpiece and get at 



§2 THE AIR BRAKE. 19 

it from below. This, of course, would not be attempted on 
the road. 

If the main valve can be raised and the pump started, the 
governor should be cut out of service by means of a blind 
gasket, as explained in Art. 4, and care should be taken that 
steam is not again entirely shut off during the remainder of the 
run, as, otherwise, the trouble might occur again, especially if 
the main-valve rings are much worn. 

2. Main-Valve or Reversing- Piston Rings Defective. — Cases 
have been known where broken main- valve rings have blocked 
the valve, and prevented its movement, thereby stopping the 
pump. A bad leak past the reversing piston, due to broken 
packing rings, will allow so much steam to escape that the 
pressure in chamber d will be reduced considerably, and a 
sufficient back pressure may be exerted on the under side of 
this piston to prevent the pump reversing its motion. 

3, 4. Defective Reversing Rod or Plate. — A broken reversing 
rod, or a loose or worn-out reversing plate, will also prevent 
the pump from being reversed. 

If, every time the pump throttle is closed for a few minutes 
and then reopened, the pump takes an up-and-down stroke 
and then stops, it is an indication that for some reason the 
reversing valve 16 has not moved to its lower position, and the 
pump should be examined for the cause. 

5. Loose Air-Piston Nuts. — If the trouble is due to none of 
the above causes, remove the lower air-cylinder head and 
examine for loose or broken nuts 58 on piston rod, for pieces of 
broken air valve, or for dirt between piston and cylinder head, 
which prevents the pump completing its stroke and operating 
the reversing valve. 

6. Pump Run Dry. — The part that is most affected when 
a pump is allowed to become very dry is the reversing piston, 
and this is consequently liable to stick and stop the pump 
for want of lubrication. A light tap will frequently start it 
again, in which case oil should be used freely to protect the 
pump against the possibility of cutting. 



20 THE AIR BRAKE. §2 

If either an 8-inch or a 9J--inch pump stops, it can, in most 
cases, be started again by first closing the pump throttle until 
all the steam in the pump has condensed, and then opening- 
it quickly. 

QUICK-ACTION TRIPLE VALVE. 



TIME REQUIRED TO CHARGE AUXILIARIES. 

21. The Effect of the Size of the Feed Groove. — The 

triple valve, like any other mechanism that is used under 
varying conditions, and is subject to rough treatment, is liable 
to certain disorders, and it is of these that we will now treat. 

As soon as an engine is coupled to a train, the engineer 
charges the latter. Air from the main reservoir is forced back 
through the train pipe, thence through the feed grooves of the 
triples, and into the auxiliary reservoirs. The feed groove is 
made of such a size that, with a constant train-line pressure of 
70 pounds, it will charge an auxiliary from to 70 pounds 
in about 70 seconds. A train with fifty auxiliaries would 
charge as quickly as a single auxiliary, if the pump could keep 
the train-pipe pressure constant at 70 pounds; but, as it cannot 
do this, more than 70 seconds is required to charge the train. 
On a train of only four or five cars, the auxiliaries will charge 
in about the same length of time as a single auxiliary; but, 
with longer trains, the time of charging depends on the size and 
condition of the pump, the number of auxiliaries to be charged, 
and the extent of leaks in the train pipe and auxiliaries, etc. 

The feed grooves in some of the first quick- action triples were 
made smaller than the present ones, and, consequently, one of 
these triples required about 2| minutes to charge an auxiliary 
with a constant train-line pressure of 70 pounds. Many of the 
plain triples, on the other hand, had feed grooves that were too 
large for the volume of the auxiliaries they controlled; conse- 
quently, these auxiliaries could be charged in about 40 seconds 
under the same conditions. 

2 2 . Auxiliary Charges Too Slowly. — As already stated , 
the feed groove is of such a size that, with everything in good 



§2 THE AIR BRAKE. 21 

condition, it will charge an auxiliary from up to 70 pounds in 
about 70 seconds from a train-line pressure of 70 pounds. The 
time of charging, however, does not depend entirely on the 
feed groove; the auxiliaries may charge more slowly from 
any of the following causes : The small openings in the strainer of 
the drain cup, Fig. 1, or in the strainer 16 in the triple valve, 
Fig. 9, may be partially stopped up, so as to restrict the flow of 
air to the triple valve; the feed groove may be partially closed 
with gum or dirt; or the auxiliary reservoir may leak. 

If oil, cinders, scale, pipe fins, etc. get into the train pipe, 
they may clog the strainers and feed grooves, get into the 
graduating valve and hold it from its seat, unseat the triple 
slide valve, or cause wear that will allow auxiliary pressure to 
escape to the atmosphere. Dirt and cinders will work into 
the train line if the brake hose is not hung up properly when 
not in use; scale may come from the inside of the pipes, if 
they are not properly treated before being applied to a car, or 
if they corrode; or oil may bake in the pump, and scale off, 
and work back into the brake system; also, pipe fins, if not 
removed by the pipemen, may work loose and cause trouble. 

23. Effect of Working Conditions. — It will thus be 
seen that the conditions of strainers and triples may not be the 
same on any two cars of a train; hence, the time required to 
charge the different auxiliaries may vary considerably, and, 
when possible, sufficient time should be allowed for all the 
auxiliaries to become fully charged before the brake valve 
is placed on lap, or the brakes applied again. If the valve is 
lapped while some of the auxiliaries are undercharged, they will 
continue to take air from the train line until they equalize with 
it, and thus may reduce train-line pressure sufficiently to apply 
the brakes on the cars on which the auxiliaries were fully 
charged. On the other, hand, if a service reduction is made 
while some of the auxiliaries are undercharged, the latter may 
not apply the brakes on their cars at the first reduction, and 
they will continue to take air from the train line until they 
equalize with it; in this case, the other brakes will set harder 
than is intended. 



22 THE AIR BRAKE. §2 

EFFECT OF TRAIN-PIPE AND AUXILIARY LEAKS. 

24. Train-Pipe Leaks. — Leaks in the train pipe not only 
increase the time required to charge the auxiliaries, but, after 
the brakes are applied, they cause the triples to gradually 
apply the brakes harder, or, as is usually said, the brakes 
11 creep on. " A leak at any part of the train pipe affects all the 
triples, since the train pipe is continuous throughout the train. 

25. Auxiliary-Reservoir Leaks. — As long as the brakes 
are off and the triples are in release position, the pump will 
make good any leakage of auxiliary pressure, and no harm will 
be done, aside from keeping the pump at work to supply the 
leak. When the brakes are applied, however, and the triple 
slide valves are in service position, a reduction of pressure in any 
auxiliary will allow train-line pressure to force its triple piston 
to release position, and release the brake on that car. Then, 
since the feed groove is open in this position, air from the train 
pipe will feed into the auxiliary to supply the leakage and to 
charge the auxiliary to train-pipe pressure; hence, a reduction 
will be made in train- pipe pressure, that will tend to apply the 
other brakes harder. It is possible, however, for the auxiliary 
reservoir to leak, and still not cause the brake to "leak off" or 
release. If train-pipe leaks reduce train-pipe pressure at the 
same rate that the leakage from the auxiliary reduces auxiliary 
pressure, the brake will not leak off; or, if the packing ring 6 is 
much worn, sufficient air may leak past into the auxiliary reser- 
voir to supply the leakage and thus prevent the brake releasing. 

Leakage of auxiliary air at the triple exhaust is generally 
due to dirt on the seat of the slide valve, a worn slide-valve 
seat, a leak in the gasket that is between the triple valve and 
the brake c} T linder (see passenger equipment, Fig. 8) or in the 
gasket 15 that is between the triple valve and the auxiliary 
reservoir in the freight equipment, Fig. 10. 



IMPORTANCE OF GRADUATING VALVE. 

26. The graduating valve 7, Fig. 9, is the part of the triple 
that makes it most sensitive. If there were no graduating 
valve, but simply the service or graduating port z, and the 



§2 THE AIR BRAKE. 23 



slide valve were fastened firmly to the stem of the piston, 
the brakes could still be applied and released, but the triple 
valve would not be nearly so sensitive, and great reductions 
would be necessary to move the parts. For instance, when a 
reduction of train-pipe pressure was made, the triple would 
assume service position; but it would not assume lap position 
again until a sufficient difference of pressure existed between 
the auxiliary and the train line to allow the latter pressure to 
overcome the friction, not only of the triple piston packing ring, 
but also of the slide valve, in which case the latter would be 
forced back far enough to close the service port z (lap position). 
Then, when it was desired to apply the brake harder, a much 
greater train-pipe reduction than usual would be necessary to 
move the triple piston to service position again, since the 
auxiliary pressure would have to overcome the friction of 
the slide valve as well as of the triple piston. 



TRIPLE-VALVE LEAKS AND DEFECTS. 

27. Blow at Triple Exhaust. — If a blow occurs at the 
exhaust port of the triple, it may be caused by any of the fol- 
lowing: (1) A leaky slide valve; (2) dirt on the seat of the 
emergency valve 10, Fig. 9, or a worn-out rubber seat 11; 
(3) a leak in gasket 14- between the passage a and the 
chamber i"; (4) a leak of auxiliary air from chamber Y to 
the passage d, owing to defective gasket between brake- 
cylinder head and triple valve, Fig. 8; (5) a leak from the 
auxiliary through gasket 15 in the freight equipment; or 
(6) the pipe b, which leads from the triple through the 
auxiliary to the brake cylinder, might be leaking. 

1. Leaky Slide Valve. — This will generally cause a blow at 
the exhaust port of the triple, regardless of whether the slide 
valve is in service or in release position, since, in either position, 
auxiliary pressure can feed across the face of the valve into the 
exhaust cavity g, and out to the atmosphere through ports h 
and k (see Fig. 9). With a leaking slide valve, the tendency 
for the brake, when set, is to release itself, since auxiliary 
pressure is, in that case, being reduced. 



24 THE AIR BRAKE. 



Dirt on the seat of this valve will cause a constant leak at the 
triple exhaust; it will also cause the brake to be very erratic in 
its action, as sometimes the slide valve will seat properly and 
the brake remain set, while, at others, the dirt will allow 
auxiliary air to escape to the atmosphere across the face of the 
slide valve, and release the brake after being applied. A 
thorough cleaning of the triple is the proper remedy in 
such a case. 

2. Emergency Valve Leaking. — If the emergency valve leaks, 
the blow at the exhaust port will cease, as explained above, if 
the exhaust port is closed by applying the brake. 

If a strong, heavy blow exists at the triple exhaust, and the 
brake will not release on that car, the emergency piston 8 is, 
perhaps, being held down so as to keep the emergency valve 10 
unseated. In this position, the train-pipe pressure raises 
check 15, air passes into the brake cylinder through the large 
ports faster than it can escape to the atmosphere through the 
slide valve and exhaust ports, and the brake remains applied, 
because air is entering the brake cylinder faster than it can 
escape. A light tap on the outside of the triple will generally 
cause the emergency valve to seat. 

When the emergency valve leaks, there is a constant leak 
from the train pipe through the quick-action part of the triple 
into the brake cylinder. If the triple is in release position, the 
air feeding into the cylinder escapes to the atmosphere through 
the triple exhaust; if the brake is set, the air cannot escape, 
and the train-pipe and brake- cylinder pressures equalize. and 
apply this brake hard. If the leaky triple is in a long train, in 
which the volume of train-pipe air is comparatively great, the 
brake cylinder will equalize at such a high pressure, on the 
first light service reduction, that the wheels on that car will 
probably be slid. 

3, 4, 5, 6. The Other Causes. — When the triple is in release 
position, the leak will, in these cases, and also in case 2, allow 
air to reach the brake cylinder, and pass through the slide- 
valve exhaust cavity into the atmosphere; but, when the brake 
is applied, the exhaust cavity of the slide valve no longer 



§2 THE AIR BRAKE. 25 

connects port / with the exhaust port h, and so the blow does 
not occur at the exhaust. In this case, the air continuing to 
leak into the brake cylinder will apply the brake harder. If 
auxiliary pressure leaks into the brake cylinder, the tendency 
will be to release the brake; while, if the train line feeds the 
leak, the brake will be set tighter, and the leakage will also tend 
to set the other brakes tighter by reducing train-line pressure. 
Of the possible sources of leakage given, the two that are 
most frequently met with are the slide valve and the emer- 
gency, or rubber-seated, valve. 

28. Other Common Defects. — The most common causes 
of trouble in the quick-action triple valve are: (1) strainers 
stopped up; (2) dirt on the seat of the graduating valve; 
(3) defective graduating spring; (4) triple gummed up; 
(5) broken graduating pin, and (6) triple freezing up. 

1. Strainers Stopped Up. — Sometimes a triple valve will not 
set the brake on a car in response to either a light or a heavy 
train-pipe reduction. This may be due to the strainers being 
partly stopped up; or the triple may be so gummed up and 
dirty that the triple piston cannot move. 

When a quick- action triple in a train applies a brake in 
emergency, the quick-action part of the triple takes air from the 
train pipe suddenly and puts it into the brake cylinder. This 
sudden reduction is sufficient to start the next quick-action 
triple into emergency, the next one following, and so on through- 
out the entire train. If two or three cars with dirty strainers, 
or a couple of old cars with plain triples, are placed together 
in a train, the sudden reduction made by the quick-action triple 
ahead of these will not be sufficient to work the next quick- 
action triple immediately behind them, owing to the effect of 
friction on the flow of air through the train pipe destroying the 
suddenness of the reduction; hence, the quick- action effect 
cannot be obtained on these cars or on the ones back of them. 
On the other hand, if the engineer makes an emergency applica- 
tion with this train, and laps the brake valve too quickly, the 
air from the rear cars will flow ahead and kick off the head-end 
brakes, and only a light service application will be obtained on 



26 THE AIR BRAKE. §2 

the brakes back of the ones causing the trouble. If the brake- 
valve handle is left in emergency position a sufficient length of 
time, however, full emergency action will be had on the cars 
ahead, and full service on those back of the ones causing the 
trouble. 

2. Dirt on the Seat of the Graduating Valve. — This will produce 
no ill effect when the triple is in release position, as the service 
port z is then closed by the slide-valve seat, and it will make no 
difference whether the graduating valve is open or closed. In 
lap position, however, this will cause a leak, which will allow 
auxiliary air to escape through the graduating valve and ports 
z and /into the brake cylinder, thus applying the brake harder 
and reducing auxiliary pressure. 

Whether this reduction will allow the brake to release 
depends on whether the triple piston packing ring is tight or 
not. If it is tight and the auxiliary is in good condition, then 
auxiliary air will continue to leak into the brake cylinder 
until a sufficient difference of pressure exists between the train 
line and the auxiliary to start the slide valve moving, when it 
may move to release position and release the brake. If, how- 
ever, air can leak by the piston packing-ring into the auxiliary 
reservoir as fast as it leaks by the graduating valve into the 
brake cylinder, the brake wall continue to set harder instead of 
releasing. With a full application of the brakes, the auxiliary 
and brake- cylinder pressures are equal; therefore, under such 
conditions, a leaky graduating valve cannot release the brake 
unless the brake cylinder also leaks and reduces the auxiliary 
pressure at the same time. 

3. Defective Graduating Spring. — The effect produced by a 
weak or broken graduating spring 22 depends on the length 
of the train. The duty of this spring is to prevent the parts 
of the triple valve from moving past service position, view (d), 
during a service application of the brakes. If the spring is 
broken or is too weak to stop the parts at service position, 
and if the train is a short one of seven cars or less, these parts 
will move to emergency position and apply the brake quick 
action, the other brakes, of course, following suit. With a long 



§2 THE AIR BRAKE. 27 

train, on the other hand, the graduating spring can be removed 
entirely and not cause the brake to apply quick action. 

The explanation of the foregoing is as follows: Since the 
graduating valve is open, auxiliary pressure begins to discharge 
into the brake cylinder as soon as port z of the slide valve 
arrives above port / in the seat. Now, whether the parts will 
move beyond this position and cause an emergency application 
of the brakes, depends on whether the train-pipe or the auxiliary 
pressure reduces the more quickly. A short train pipe contains 
a comparatively small volume of air; this discharging through 
the brake valve has its pressure reduced at a much greater rate 
than the auxiliary pressure that reduces through the gradu- 
ating valve; hence, as soon as a sufficient difference in pressure 
is formed, the parts of the triple valve are moved forwards, 
and the brakes are applied in emergency. With a long train, 
however, the volume of air in the train pipe and the frictional 
resistance to its movement are so much greater that train-pipe 
pressure cannot be reduced through the train-pipe exhaust 
of the brake valve as fast as auxiliary pressure is reduced 
through the graduating valve. As a result, train-pipe and 
auxiliary pressures remain about equal, and a sufficient differ- 
ence of pressure is not formed after service position is reached 
to move the parts of the triples to emergency position. 

4. " Sticky" Triples. — A sticky triple is frequently the 
cause of the brakes applying quick action during a gradual train- 
pipe reduction. Generally, when a triple sticks, it does not 
respond to the first service reduction, nor, in some cases, to the 
second, and the brake on that car does not set; usually, with the 
next reduction, the difference in pressure between the auxiliary 
and the train line is such that the triple piston is torn loose 
from the gum and caused to move quickly forwards, compress- 
ing the graduating spring 22, and moving the slide valve to 
emergency position. The sudden train-pipe reduction caused by 
the quick-action part of the faulty triple coming suddenly into 
play, starts the next triple into quick action, which affects the 
one following, and so on throughout the train. 

5. Broken Graduating Pin. — If the pin that fastens the 
graduating valve 7 to the stem of the triple piston is broken, 



28 THE AIR BRAKE. 



the graduating valve will be held on its seat by auxiliary 
pressure, and the brake on that car will not apply until a 
sufficient reduction is made to move the triple slide valve to 
emergency position, when it will set quick action. With a 
light service reduction, the triple assumes service position, but 
the graduating valve being on its seat, no air can pass from the 
auxiliary to the brake cylinder, and the brake does not apply on 
this car. With only a light reduction, the auxiliary pressure 
acting on the triple piston is not sufficient to compress the 
graduating spring, but, when a second train-pipe reduction is 
made, the auxiliary presssure is sufficiently greater than that 
in the train pipe to force the triple piston out and compress 
the graduating spring, and the triple then assumes emergency 
position. If the graduating valve is so badly gummed up that 
air can only escape very slowly through it, the effect will be the 
same as though the graduating pin were broken. 

6. Triple Freezing Up. — Water sometimes accumulates in 
the drain cup of the triple valves. In cold weather, this water, 
may freeze and cause trouble. In thawing out a triple, always 
remove the drain plug and drain off the water to avoid a recur- 
rence of the trouble. The water found in the brake system 
comes mostly from the moisture drawn into the pump along 
with the air; as the air is compressed, this moisture is given up, 
and some of it works back into the brake system. 

29. ^Locating the Cause of Trouble. — To locate a 
sticky triple, or one with a broken or badly gummed-up 
graduating valve, make a service reduction that is not quite 
sufficient to cause the defective triple to operate quick 
action, and then look for the brake that has not set. Cut 
this one out, and repeat the test to make sure the trouble 
has been properly located. If all brakes go into emergency 
with the first light service reduction, the only way to locate 
the faulty triple will be to first close an angle cock in the 
middle of the train, and try to locate the trouble in one half 
first; then proceed in the same manner with the half that 
is known to contain the faulty triple, and so on until the 
search has been narrowed down to four or five cars. The brakes 



§2 THE AIR BRAKE. 29 

may then be applied and the pistons of these cars watched 
to see which one jumps first, or the cars may be cut out one 
at a time until the trouble is located. 



PLAIIST TRIPLE VALVE. 



WHERE USED. 

30. The plain triple valve, Fig. 7, is usually found only on 
engine, tender, and old passenger-car equipments. The parts 
of this triple correspond to the service parts of the quick-action 
triple, and they are liable to the same disorders. The gradua- 
ting spring 10 in the plain triple serves the same purpose as the 
one in the quick-action triple, but it is comparatively of little 
importance, since, when a plain triple goes into emergency, 
it does not affect the other triples, as it does not take air 
from the train pipe. 

LEAKS AND OTHER DEFECTS. 

31. Leaks. — Among the most common sources of trouble 
in the plain triple are leaky slide and graduating valves, or 
a blow at the exhaust port. 

Leaky Valves. — A leaky slide valve or graduating valve will 
affect the brake in the same manner as the same defect in a 
quick-action triple would, 

Triple Exhaust Blowing. — A blow at the exhaust port k 
may be caused by a leaky slide valve 3 or plug cock 13. As 
in the case of the quick-action triple, there will be a continuous 
blow at the exhaust port if the slide valve leaks, regardless of 
whether the brake is applied or released. If the plug cock 13 
leaks, and the slide valve is in release position, air from the 
train line entering at W will leak by the plug valve into port e ) 
thence through port ./, cavity g of the slide valve, and ports h 
and k, to the atmosphere. If the brake is set, the slide valve 
will be in such a position that cavity g will be closed to port /, 
and the blow at the exhaust will cease; but the air leaking by 
the plug cock will pass out to the brake cylinder at Xand set 



30 THE AIR BRAKE. §2 

this brake tighter. With the plug cock leaking, the train-pipe 
and brake- cylinder pressures will gradually equalize, and, on a 
long train having a large volume of air in the train pipe, the 
train-pipe and brake-cylinder pressures might equalize suffi- 
ciently high to slide the wheels. 

32. Other Defects. — Under this heading may be men- 
tioned defective rings and the freezing up of the triple. 

Defective Rings. — A worn piston packing- ring 6 will allow air 
to feed by the piston, and may charge the auxiliary too quickly. 
On a long train, a slow train-pipe reduction might allow 
auxiliary pressure to feed back through the feed grooves m 
and w, and past the packing ring, sufficiently fast to keep equal 
with train-pipe pressure, in which case the triple piston would 
not be forced out, and the brake would not apply; or in 
releasing brakes, if train-pipe pressure is increased slowly, it 
might feed by the packing ring sufficiently fast to charge the 
auxiliary and leave the brake set. 

Triple Freezing Up. — Water may collect in chamber A; in 
cold weather, therefore, the latter should be drained frequently 
by partially unscrewing the lower cap nut 11. 



CARE OF TRIPLES. 

33. Triple valves should be inspected and thoroughly 
cleaned and oiled at least once every six months. In cleaning 
the triple, it is a good idea to immerse the triple piston in 
kerosene while cleaning the other parts. The emergency parts of 
the quick-action triple should be removed, examined, and 
cleaned, and then replaced without oiling, as these particular 
parts are seldom used, and oil would only serve to collect dirt. 
The slide valve and the chamber in which it works should be 
thoroughly cleaned, and great care should be exercised to 
remove any lint from the valve or its seat. The graduating 
valve and all small ports should be carefully cleaned. After 
everything else has been attended to, the triple piston packing 
ring should be cleaned carefully, without being removed from 
the piston, as in so removing it there is great danger of springing 



§2 THE AIR BRAKE. 31 

the ring out of. true. Before replacing the piston, the ring should 
move freely to the touch, and in entering the piston into its 
bushing, care should be taken not to bruise the packing ring. 

The graduating stem should be forced in with the thumb to 
make sure that the graduating spring is doing its work properly. 
The only parts of the triple that need oiling are the triple 
piston packing ring, the bushing in which it works, and the 
face of the slide valve; sufficient oil can be held on the end of 
the ringer to oil these parts. Too much oil is a detriment 
rather than a benefit, since it collects scale and dirt. The 
strainer in the triple, and the one in the train-pipe tee, where 
the branch pipe couples on, should always be kept clean. 



FREIGHT EQUIPMENT. 



LEAKS A:NT> OTHER DEFECTS. 

34. Leaks. — In addition to the causes of trouble already 
given as occurring in the triple itself, the freight equipment 
shown in Fig. 10 is liable to various leaks, as follows: 

Defective Gasket. — The gasket 15 between the triple valve and 
the auxiliary may leak, allowing air to pass from the auxiliary 
into pipe b, and thence to the brake cylinder; or, from the 
auxiliary to the atmosphere. The leak between the auxiliary 
and the brake cylinder will cause a blow at the triple exhaust 
port when the triple is in release position. After the brake is 
applied and the triple is in service position, however, the 
leakage of auxiliary air across the gasket, either to the brake 
cylinder or the atmosphere, will tend to release the brake. 

Pipe Leaking in Auxiliary. — If pipe b leaks inside of the 
auxiliary, the same effect will be noticed as if the gasket 15 
leaked between the auxiliary and pipe b. 

Leaky Valves.— k leaky release valve 1 7 will allow a constant 
escape of auxiliary air to the atmosphere. With the triple 
valve in release position, the pump will supply this leak and 
no ill effect will be noticed aside from the extra work, put on 



32 THE AIR BRAKE. §2 

the pump; when the brake is applied, however, the escape of 
air reducing the auxiliary pressure will tend to release it. 

35. Other Defects. — There are also certain other defects 
of the various parts that may give trouble. 

Split Sleeve. — The sleeve 3 sometimes splits, owing to the side 
motion of the push rod that works inside it. When this 
occurs, the release spring cannot force the brake piston to 
release position when brakes are released, as it binds in the 
hood of the cylinder; consequently, the brake shoes tend to 
drag on the wheels. 

Defective Spring. — If the release spring 9 is weak, it will not 
force the brake piston to release position properly, especially if 
the cylinder is somewhat dirty; as a result of this, the piston 
may stay out after the triple has moved to release position and 
allowed the air to escape from the cylinder. In such a case, 
the sleeve and piston will gradually work in when the car is 
moving, since the jar of the wheels against the shoes will work 
them away, and cause the rods and levers to assume their 
normal release positions. 

Defective Packing. — If the packing leather 7 is cracked or worn 
through on the bend of the flange, it will be impossible to set 
that brake and keep it on, for, as the air enters the cylinder, it 
will escape past the piston, and the brake will gradually leak 
off. Sometimes a brake in this condition will not apply with a 
service application, but will do so with an emergency applica- 
tion, after which it gradually leaks off. 

Leakage Groove Stopped Up. — If the leakage groove a becomes 
stopped up with dirt or gum, and the piston travel happens to 
have been taken up short enough, the pressure on the brake piston 
may get so high that the wheels on this car may slide when 
the brakes are applied. If such a <jar were near the rear of a 
long train, the train pipe of which leaked, the reduction due to 
the leak might work the triple piston out far enough to close 
the exhaust port and allow some of the auxiliary-reservoir air 
to reach the brake cylinder. The air feeding in slowly would 
blow through the leakage groove were it open; but, being 



§2 THE AIR BRAKE. 33 

closed, the brake of this car would gradually apply and might 
stall the train. 

Expander Ring Out of Place. — The duty of the expander ring 8 
is to hold the flange of the packing leather against the walls of 
the cylinder. If the expander ring worked out, due to its not 
being put in properly, the flange of the leather would drop 
down, and all air entering the cylinder would probably escape 
past the piston to the atmosphere. 



CARE OF EQUIPMENT. 

36. Cleaning and Oiling the Cylinder. — When the 
cylinder head and piston are removed, the walls of the cylinder 
should be thoroughly cleaned with waste saturated with 
kerosene, and special care should be exercised to free the 
leakage groove of all dirt or gum; the cylinder should then 
be wiped dry. 

The expander ring should be removed, and both that and 
also the groove in which it rests be thoroughly cleaned; then, 
before the ring is replaced, a small amount of oil should be put 
into the groove. Before replacing the piston, the cylinder walls 
should be thoroughly oiled or greased, by covering the hand 
with the oil or grease and then rubbing the walls with the 
hand. When the cylinder is oiled through the oil plug 16, care 
should be taken not to put in so much that, when the piston is 
moved to release position, the oil will be forced through pipe b 
into the triple, as this will decay the rubber-seated valve and 
render the triple useless until repaired. 

37. Cleaning and Oiling Triples. — In cleaning and 
oiling triples, all parts should be thoroughly cleaned. It is 
not necessary to oil the emergency parts, and sufficient oil can 
be held on the end of the finger to oil the slide valve, its 
bushing, the triple piston packing ring, and the bushing -in 
which it works. The strainer, where the branch pipe couples 
to the triple, should also be cleaned, as wel\ as the one where 
the branch pipe joins the main train pipe. 



34 THE AIR BRAKE. §2 



RETAINING YALYE, 



its duty a:nt> operation. 

38. Duty. — The primary object of the retaining valve is 
to retain a pressure of 15 pounds in the brake cylinder, during 
the time the triple is in release position, while the engineer is 
recharging the auxiliaries in descending a grade. It has no 
effect whatever on any brake except that of the car on which it 
is placed, and it only affects the releasing of that brake, since 
it merely retains 15 pounds pressure in the brake cylinder. 

The retainers, however, often perform another duty, namely, 
to keep the slack of a freight train bunched after brakes have 
been released, and the train is drifting preparatory to making 
a stop. Two or three of the head-end retainers judiciously 
used in such a case will often prevent a bad jar at the rear 
of a train. 

The retainer is used on almost all cars in freight service, and, 
in mountainous districts, on passenger cars also. A retainer 
when in service holds 15 pounds pressure in the brake cylinder, 
while the brake is released, regardless of whether the piston 
travel is long or short. 

39. Testing. — To test a retaining valve, the handle should 
be turned up and the engineer then signaled to apply and 
release the brakes. Shortly after air ceases to discharge from 
the retainer, the handle should be turned down, and, if air dis- 
charges through port e, the retainer may be considered to be 
all right. 

40. Use on Grades. — In using the retaining valves on a 
grade, it is best not to raise the handles until the train is round- 
ing the summit of the hill. If the retaining handles are turned 
up before the summit is reached, and the leakage groove in any 
of the brake cylinders should happen to be stopped up, any 
leak that would allow air pressure to reach that cylinder would 
set the brake, and perhaps stall the train. 



§2 THE AIR BRAKE. 35 



GAINS DUE TO USE OF RETAINING VALVE. 

41. The following remarks will give an idea of the gain 
effected by using the retaining valve in handling trains on 
grades: With train pipe and auxiliary fully charged, and the 
piston travel adjusted to 8 inches, a 5-pound train-pipe reduction 
will give a brake- cylinder pressure of about 10 pounds; with 
this brake full-set, a pressure of about 50J pounds is developed 
in the brake cylinder. If the retainer handle is now raised, and 
train-pipe pressure is increased so as to force the triple-valve 
piston to release position, the auxiliary will be recharged to 
70 pounds, while the brake cylinder will retain 15 pounds. This 
will cause the brake cylinder and auxiliary to equalize on 
succeeding applications at about 56 pounds, instead of 50, as 
long as the retaining valve is cut in. This not only gives a 
greater braking power, but also saves air, since a reduction of 
only about 15 pounds is necessary to make a full application 
of the brakes. Then again, with 15 pounds already in the 
brake cylinder, a 5-pound reduction will give a brake-cylinder 
pressure of about 38 pounds. It is thus seen that by using 
retainers, a large gain in braking power is made with the first 
5-pound reduction, a gain is made when the brake is full-set, 
less air need be wasted to apply the brake in full, and less time 
is required to recharge after a release is made. 

With the piston travel adjusted to 8 inches, an emergency 
application without a retaining valve develops about 57^- pounds 
in the brake cylinder, while, with a retaining valve, a brake 
cylinder pressure of about 62 pounds is developed. This also 
shows a slight gain in favor of the retaining valve. 

The gain made with a 5-pound train-pipe reduction, after the 
retaining valve is cut in, appears, at first glance, to be out of 
proportion, but it should be remembered that, when the retain- 
ing valve is not in use and a train-pipe reduction is made, part 
of the first auxiliary air that enters the brake cylinder escapes 
through the leakage groove to the atmosphere, before the 
piston has moved out far enough to close it. Some air also 
blows past the packing leather before the flanges are forced 
tightly against the cylinder walls. This loss does not occur 



36 THE AIR BRAKE. §2 

when the retaining valve is in use, as the 15 pounds retained 
by it holds the piston out far enough to cover the leakage 
groove; it also holds the flanges of the packing leather against 
the cylinder walls. 

It will thus be seen that a retaining valve is not only an aid 
in controlling the speed of the train while on a down grade, 
during the time the pump is recharging the auxiliaries, but it 
is also an adjunct that causes a more powerful braking force to 
be developed while it is in use. 

The figures given are for a retaining valve that holds the full 
15 pounds in the brake cylinder. This amount has been found 
by repeated tests to be the standard pressure for cars in inter- 
change service. This pressure gives good results in braking on 
long grades, without excessive heating of wheels. 



LEAKS AND DEFECTS. 

42. The retaining valve, Figs. 12 and 13, will be rendered 
useless by any of the following defects: (1) A leak at the union 
in the retainer pipe near the triple valve. (2) A leaky plug 
cock 6 that allows the pressure that should be retained in the 
brake cylinder to leak by the plug valve into port e, and thence 
to the atmosphere. (3) Dirt on the seat of the weighted 
valve ^, which will hold the valve from its seat and allow the 
air to pass by the valve and out to the atmosphere at port d. 
(4) A leak at the joint where the retainer screws on to the 
retainer pipe, which also allows the brake-cylinder pressure to 
escape to the atmosphere. (5) A split in the pipe leading to 
the retaining valve, or a leaky packing leather in the brake 
cylinder; either of these defects will produce the same effect as 
an imperfect retaining valve. (6) Port d being stopped up; 
for all the air will be retained in the brake cylinder when the 
brakes are released, and, consequently, the brake will remain 
set with full force. (7) If the retaining valve is not placed 
perpendicularly on the car, the weight will not hold the valve 
on the seat, and air will leak past. 



§2 THE AIR BRAKE. 37 



D-8 BRAKE VALVE. 



DEFECTS. 

43. Testing Excess-Pressure Spring. — If the pump is 
started with the brake valve in full release, both red and black 
gauge hands should move up together, as, in this position, main- 
reservoir, equalizing-reservoir, and train-pipe pressures are all 
directly connected. If the gauge hands do not stay together, 
the gauge is incorrect, and should be reported for adjustment. 
With this valve, the pump governor is operated by train-pipe 
pressure; consequently, it stops the pump when train-pipe 
pressure reaches 70 pounds, and, with the brake valve in release 
position, both hands of the gauge should register this amount 
when the pump stops. 

If the pump is started with the valve handle in running 
position, the red hand should be 20 pounds in advance of the 
black one; and, when the pump stops, the black hand should 
register 70 pounds and the red hand 90. If the black hand 
indicates 70 pounds, but the red hand indicates less than 90, 
the excess-pressure spring 20, Fig. 14, is either too short or too 
weak. If the black hand stands at 70 pounds and the red 
above 90, the excess-pressure spring is too stiff, or the valve 21 
needs cleaning, to make it work more freely. 

Should the spring 20 break, lengthen the longer piece by 
stretching until it will hold the excess-pressure valve to its 
seat with sufficient force to maintain, as nearly as possible, the 
proper excess pressure. If the spring breaks near the middle, 
it may be necessary to force a small piece of wood into the 
valve 21, so as to partially fill it and thus compensate for the 
short spring. The broken spring should be replaced by a new 
one at the first opportunity. 

If the spring is too weak, it should be removed and lengthened 
by stretching until of the proper strength. If too stiff, it should 
be shortened by cutting off a piece. If, when the pump stops, 
the black hand registers either more or less than 70 pounds, and 
the red hand shows that the proper excess pressure is main- 
tained, then the pump governor needs adjusting. To do this, 



38 THE AIR BRAKE. §2 



remove the cap nut 39, Fig. 3, and unscrew the nut ^0 to adjust 
for a lower train-pipe pressure, or screw it down for a higher 
pressure. 

44. Brake Valve Fails to Maintain Excess Pressure. 

If, with the valve in running position, both hands remain 
together all the time, and no excess pressure is maintained, 
the trouble is caused by a leaky rotary valve or by dirt 
on the seat of the excess-pressure valve 21. Sometimes this 
leak from the main reservoir into the train pipe is so slight that 
it does not affect the excess pressure when the engine is coupled 
to a train; but, when the engine is alone, no excess pressure 
can be maintained, as the train pipe equalizes with the main 
reservoir. In the former case, leaks out of the train pipe com- 
pensate for the slight leak into it; while, in the latter, the 
train pipe is so short that practically no air leaks out, in 
which case the leak into it soon causes the train pipe and main 
reservoir to equalize. 

45. Testing for Leaky Rotary. — To test for a leaky 
rotary, close the cut-out cock below the brake valve, and start 
the pump with the valve handle on lap position. In this posi- 
tion all ports are blocked, and any leak into the train pipe will 
cause a blow at the train-pipe exhaust, or will be indicated by 
the black hand of the gauge. 

A method that can be used when the brake system is charged 
is to close the cut-out cock 5 in the train pipe under the brake 
valve, make a service reduction of 30 or 40 pounds, and lap the 
valve; then, any leakage of main -reservoir air into the train 
pipe will be indicated by a blow at the train-pipe exhaust. 

Still another method is to fully charge the main reservoir 
and place the brake valve on lap; drain all air from the equali- 
zing reservoir, the engine and tender auxiliaries, and the train 
pipe, and see that all bleed cocks are closed; then open the 
angle cock at the back of tender, and place the end of the hose 
in a pail of water. Any -leakage of main-reservoir pressure into 
the train pipe will be indicated by bubbles rising to the surface 
of the water. Although this method will detect a smaller leak, 
the others are sufficiently accurate, and can be tried more easily. 



§2 THE AIR BRAKE. 39 



EXCESS-PRESSURE VALVE FAULTS. 

46. Dirt on Valve Seat. — If the rotary does not leak, 
the trouble must be in the excess-pressure valve.. In fact, 
dirt on the seat of the excess- pressure valve is generally 
found to be the source of trouble when excess pressure cannot 
be maintained. 

47. Removing the Valve. — If necessary to remove the 
excess-pressure valve 21, for cleaning or otherwise, close the cut- 
out cock 5 under the brake valve, Fig. 1, and place the valve in 
service position before attempting to remove it. Closing the 
cut-out cock retains the air in the train pipe and auxiliaries; 
while placing the brake valve in service position closes port / 
to main-reservoir pressure, and empties chamber D and the 
train pipe above the cut-out cock 5, thus removing all pressure 
from the excess-pressure valve. The valve may then be 
removed by unscrewing the cap nut 19. Clean both the valve 
and its seat thoroughly, being careful not to scrape the face or seat 
of the valve with any hard material. Before replacing, place 
the brake- valve handle in running position for a second or two, 
to blow out any loose dirt or scale that may be in the ports 
leading to the valve. 

48. Valve Stuck Shut. — Occasionally, the excess-pres- 
sure valve becomes stuck shut, so that air cannot pass through 
it into the train pipe when the brake valve is placed in running 
position. This results usually from the use of too much or 
poor oil in the air end of the pump; the oil forms a gum that 
gradually blocks the excess-pressure valve and may also cause 
trouble in other parts of the air-brake system. With the 
excess- pressure valve stuck, the engineer very often goes over 
the road with the brake-valve handle in full release, and with 
no excess pressure. This is a very bad practice and one that 
should be avoided. If the excess-pressure valve sticks, take it 
out and clean it. This can be done in a few minutes, and will 
cause very much less delay than if it were allowed to remain 
stuck and the valve carried in full release, as in the latter case 
the brakes are liable to stick after each application. If the 



40 THE AIR BRAKE. §2 



exc.-ss-pressure valve 21 works stiffly in the cap nut 19, the valve 
will be less sensitive than usual and the excess pressure will 
fluctuate; that is, when the valve works stiffly, more than 20 
pounds excess pressure must be obtained before it will open, 
while, on the other hand, it will not close until the excess 
pressure is less than 20 pounds. 

49. Leaks. — A leak in the rotary valve or past the excess- 
pressure valve that will allow train-pipe and main-reservoir 
pressures to equalize, will maintain them equal; and, since with 
this brake valve the governor is set to stop the pump as soon 
as a train-pipe pressure of 70 pounds is obtained, the pump will 
not start again until the pressure in both train pipe and main 
reservoir is reduced to that amount. Thus, a considerable 
reduction in train-pipe pressure must take place, which is 
very liable to cause the brakes to " creep on." 

50. High Excess-Pressure. — If this brake valve is lapped 
before train-pipe pressure is obtained, the governor will not 
stop the pump, which will continue to operate until sufficient 
main- reservoir pressure is accumulated to stop it. With a high 
excess pressure, as in this case, care must be exercised in releas- 
ing the brakes; that is, do not leave the valve too long in 
release, for, if the main reservoir were allowed to equalize with 
the train pipe and auxiliaries, they would be charged to such a 
pressure — especially with a short train — that it would be liable 
to burst some of the hose or else slide the wheels when the 
brakes were applied. On some roads a duplex pump gov- 
ernor is used to prevent overcharging — one side being set at 
70 pounds and operated by train-pipe pressure, the other being 
set at 90 pounds and operated by main-reservoir pressure. In 
this way, the pump is stopped as soon as either the main 
reservoir or the train pipe is charged to the desired pressure. 
This practice gives very good results. 

51. Rotary Valve Turns Hard.— When the rotary valve 
is hard to turn, it does not necessarily indicate that the valve 
needs oiling. The nut that holds the handle 8 on may be 
screwed down so tight that the gasket 12 binds. 



§2 THE AIR BRAKE. 41 



52. Peculiarity of D-8 Valve. — A peculiarity of this 
brake valve is that, if placed in a position midway between the 
service and the emergency positions — in which position the 
direct-application-and-supply port I is connected by cavity c of 
the rotary valve with the exhaust port k — the black hand of 
the air gauge, instead of dropping back to zero, will indicate 
the amount of pressure in the main reservoir. 

The reason for this is that, in this position, port j of the 
rotary valve is directly above port g in its seat; consequently, 
the equalizing reservoir equalizes with the main reservoir, and, 
since the black hand indicates the pressure in the equalizing 
reservoir, it must, in this position, indicate main-reservoir 
pressure also. 

PORT li AND POET-AND-GROOVE e. 

53. Size of Port h. — The hole through the plug in 
port h, view (6), is made of such a size that equalizing-reservoir 
pressure will be reduced from 70 to 50 pounds, in service 
position, in from 4 to 5 seconds. If it takes longer than this, 
the packing ring in the equalizing piston is probably so loose 
that the train-pipe pressure leaks into chamber D above the 
equalizing piston, or else the preliminary-exhaust port e, 
view (c), is partially closed with dirt or gum. If port e is 
closed entirely, a service application cannot be made with the 
brake valve. 

54. Small Groove in the Rotary Seat. — This groove, 
which connects with port e, is made of such a length as to con- 
nect chamber D with the main reservoir (through port j and 
the groove-and-port e) from the instant the train line is con- 
nected with main reservoir through port a, cavity c, and the 
supply port I, view (c). The combined area of the ports e 
and g, which lead to chamber D, is such that, ordinarily, 
chamber D will charge as fast or faster than the train pipe. 
Without the groove, however, the train pipe would be connected 
with the main reservoir — through port a and cavity c — both 
before portj made connection with port e, in moving the valve 
to release position, and also after it had broken connection with 



42 THE AIR BRAKE. §2 



this port in moving from release position. At such times, 
therefore, train-pipe pressure would generally increase faster 
than the pressure in chamber D; consequently, a discharge 
would probably occur at the train-pipe exhaust valve for an 
instant or two, while moving the brake valve into release 
position. 

RECHARGING SHORT TRAIN. 

55. When the train pipe is short, as, for instance, on a lone 
engine and tender, a discharge generally occurs at the train- pipe 
exhaust valve for a second or two when the brakes are released. 
The reason for this is that the capacity of the train pipe is small, 
while the ports through which it is charged are large compared 
with the area of the ports through which chamber D is charged; 
hence, the pressure in the train pipe increases faster than that 
in chamber D, and therefore raises the equalizing piston. This 
opens the train-pipe exhaust valve E, and a discharge takes 
place until train- pipe pressure is reduced below the pressure of 
chamber I), after which the valve is closed. This, will occur 
with either a D-8 or an F-6 brake valve. 

With a long train pipe, this discharge does not take place, for 
the reason that the volume to be filled is so much greater that 
the pressure in chamber D increases faster than train-pipe pres- 
sure; consequently, the equalizing piston is held on its seat. 



F-6 BRAKE VALVE. 



TESTING. 

56. Testing the Gauge. — If the pump is started with 
the brake valve in full release, the hands of the air gauge will 
move up together until they both register full main-reservoir 
pressure. The pump governor, when used with this valve, is 
operated by main-reservoir pressure, and does not stop the 
pump until main-reservoir pressure is obtained; consequently, 
the gauge hands will move up together and register the same 
pressure when the pump stops, since, in release position, there 



THE AIR BRAKE. 43 



is a direct connection between the train pipe and the main 
reservoir. If the hands do not move up together, the gauge is 
incorrect and should be reported. 

If the pump is started with the brake valve in running posi- 
tion, the hands of the gauge will move up together until full 
train-pipe pressure is obtained; the feed- valve attachment then 
closes and the black hand, consequently, remains stationary, 
but the red hand continues to move up until full main-reser- 
voir pressure is obtained. 

57. Testing the Pump Governor. — If, with a correct 
gauge, the black hand indicates 70 pounds when the pump 
stops, while .the red hand indicates either more or less than 
proper main-reservoir pressure, the pump governor needs regu- 
lating. This is accomplished by removing the cap nut 39, 
Fig. 3, and slacking the regulating nut 4.0 to regulate for a 
lower, or screwing it tighter for a higher, main- reservoir pressure. 

58. Testing the Feed- Valve Attachment. — If the red 

hand indicates the main-reservoir pressure correctly, but the 
black hand indicates either more or less than 70 pounds, then 
the feed-valve attachment needs regulating. This is accom- 
plished by removing the cap nut 71, Fig. 16 (6), and slacking 
the regulating nut 70 to reduce, or screwing it up to increase, 
the train-pipe pressure. 

LEAKS AND OTHER DEFECTS. . 

59. Feed Valve Fails to Maintain Train-Pipe Pres- 
sure. —If, in running position, the feed-valve attachment fails 
to maintain train-pipe pressure at 70 pounds, and the black 
hand gradually moves up until it indicates the same as the 
red hand, the trouble is due to a leak from the main reservoir 
into the train pipe, either through the rotary valve, the gasket 
32, the supply valve 63, or by the feed-valve case gasket 27. 

60. Leaky Rotary Valve. — A leak in the rotary valve 
generally occurs past the bridge w, so that main-reservoir pres- 
sure can pass down port a and leak into cavity c of the valve, 
thence passing to the train line through port I. Any leak from 



44 THE AIR BRAKE. 



the main reservoir into the train pipe, therefore, tends to release 
the brakes when they are applied. The test for a leaky rotary 
of an F-6 valve is the same as with the D-8. 

61. Leaky Gasket. — A leak in the gasket 32 generally 
allows main-reservoir pressure to pass from the passage X x' into 
chamber D above the piston 17, view (a). Since the capacity 
of the equalizing reservoir is small, such a leak will cause the 
black hand to quickly move up to the position of the red hand 
when the brake valve is lapped. It will also make the service 
reductions slower than usual, since the air feeding into chamber 
D tends to maintain the pressure there, and, if the leak were a 
very bad one, it would prevent any service reduction being 
made at all. With chamber D pressure greater than train-pipe 
pressure, as in the above case, air will leak past the equalizing 
piston packing ring 18 into the train pipe. 

Testing for Leaky Gasket. — A leak in gasket 32 may be detected 
by placing the brake valve on lap and watching the gauge; 
if the gasket leaks, the black hand will move up rapidly 
towards the red hand. A leak through the rotary valve or the 
gasket 32 can be readily distinguished from a leak in gasket 27 
or supply valve 63, since the former are constant while the two 
latter occur only when the brake valve is in running position. 

62. Leak Past tlie Supply Valve. — A leak past the 
supply valve may be due to a leaky valve, to the valve being 
held from its seat by dirt or gum, or to a defective diaphragm 
72, view (6). To determine which of these is causing the 
trouble, the supply valve must be removed and inspected. 

To remove the valve, close the cut-out cock 5 under the brake 
valve, Fig. 1, and place the brake valve in service position, so as 
to remove all pressure from the feed- valve attachment. Unscrew 
the cap nut 65, and remove the feed valve. 

To clean the valve, soak it in kerosene, or heat it in steam, and 
then wipe dry with clean cloth or waste. The valve seat may 
be cleaned with a piece of wood. 

The. face of the supply valve is made of soft metal, and, 
therefore, should never be scraped with any hard tool, as the 



§2 THE AIR BRAKE. 45 

valve may thus be ruined. In case of a leaky supply valve, 
grind it to a tight fit by placing carefully on its seat and 
turning with the fingers while applying a light pressure. The 
spring box 69 must be taken out and the piston 74 pulled 
down so as to allow the supply valve to rest firmly on its seat. 
Do not use emery, as it is unnecessary and will cause trouble if 
it gets into the brake system. The supply valve cannot stand 
much grinding. Before replacing the supply valve, put the 
brake valve in running position for a second or two, to blow out 
any loose dirt there may be around the supply- valve seat. 

63. Defective Diaphragm. — The edges of the dia- 
phragm 72 may be so crushed and squeezed out, if the spring 
box 69 is screwed up too tight, that the diaphragm will "arch 
up ' ' and thus almost entirely prevent movement of the feed- 
valve piston 74', consequently, the supply valve will be held 
from its seat. The spring box 69 should only be screwed up 
until a firm joint is made with the diaphragm, and not until it 
makes a tight joint with the feed-valve case 62. 

If the trouble in the feed-valve attachment is in the gasket 
27 or the supply valve 63, it may be readily repaired while on 
the road, but if in the diaphragm 72, repairs had better not be 
attempted until the end of the run. In this case, no excess 
pressure can be carried, and train-pipe pressure will have to be 
regulated by means of the pump throttle. 

64. Feed- Valve Piston Sticking. — Trouble is some- 
times experienced in removing piston 7 4, on account of its 
sticking. In such a case, proceed as follows: Remove the 
supply valve 63 as described, and replace the cap nut 65) 
unscrew the spring case 69, grasp the stem 66 of the piston in 
the right hand, and move the brake-valve handle carefully to 
running position. Main-reservoir pressure acting on top of 
piston 74- will blow it out. When replacing the piston, be sure 
that packing ring 67 works freely, and do not bruise it by 
pounding in getting the piston back. 

65. Leaky Feed- Valve Case Gasket. — A leak some- 
times occurs in the gasket 27, between the feed ports/'/" and i, 
which allows main-reservoir air to pass directly into the train 



46 THE AIR BRAKE. §2 



pipe when the brake valve is in running position. This can 
sometimes be stopped by simply tightening the nuts of the 
feed- valve studs, view (e). If it cannot, then close the cut-out 
cock under the brake valve, place the valve in service position, 
remove the feed-valve case from the brake-valve body, and 
replace the blown-out gasket with a temporary one made of 
pasteboard, part of an old felt hat, or of anything similar that 
is at hand. 

66. Jlieaky Train-Pipe Exhaust Valve. — Sometimes 
the train-pipe exhaust valve E is held from its seat by dirt or 
gum. This causes a continual blow at the exhaust valve, and, 
consequently, when the brake valve is on lap the brakes will 
gradually set harder. It may be possible to close the train-pipe 
exhaust valve by quickly moving the brake valve from full 
release to emergency and back again a couple of times. If not, 
the equalizing piston will have to be removed and cleaned. 

67. Preliminary-Exhaust Port Plug. — The size of the 
passage through the plug in preliminary-exhaust port e is such 
that, during a service reduction, equalizing-reservoir pressure 
should be reduced through it from 70 to 50 pounds, in about 
5 seconds. If it does not, the trouble is due to one of the 
following causes: Either the size of this passage is reduced 
owing to the presence of gum and dirt; or, the piston packing- 
ring 18 is so worn that train-pipe air can pass by it into 
chamber D; or, the gasket 32 is leaking. 



CARE OF ENGINEER'S VALVES. 

68. General Remarks. — There is a wide range of varia- 
tion in the time a rotary valve will continue working satisfac- 
torily in general service. Some valves will run three, four, or 
six months, while" others will not run as many weeks. 

Tallow or vaseline are good lubricants for the rotary, but oil 
of any kind should be used sparingly on any part of the brake 
apparatus, except the steam end of the pump. Oil that has a 
tendency to gum should never be used. 



§2 THE AIR BRAKE. 47 



Whenever the rotary valve works hard, the brake valve should 
be taken apart and the rotary cleaned and oiled, to prevent 
cutting. At the same time, the packing ring 18 should be 
cleaned, but without removing it, since, if removed, it is liable 
to be sprung out of true, which will necessitate refitting to the 
bushing in which it works. Also clean the stem and seat of 
the valve E thoroughly, but leave no oil on either, as it will 
catch particles of dirt and scale and cause trouble. 

69. Rotary Working Hard. — The chief causes of a 
rotary working hard are: too free use of oil on the air end of 
the pump, or the use of poor oil; constant use of the emergency 
position of the valve, which tends to draw dirt and scale from 
the train line upon the rotary seat; a hot pump, the heat from 
which will cake the oil on the rotary seat; the nut 7, Fig. 16 
(6), or the corresponding nut in Fig. 14 (a), being screwed 
down so tight as to cause gasket 12 to bind on the top casing of 
the engineer's valve. 

70. Cleaning the Feed-Valve Attachment. — In clean- 
ing the feed- valve attachment of the F-6 valve, or the excess- 
pressure valve of the D-8 valve, remove all dirt and gum and 
clean the valve chambers thoroughly; then blow out, by turn- 
ing the brake valve to running position. Any gum present 
should be softened, if possible, and wiped out instead of scra- 
ping out with a tool that is liable to scratch the valve seat. The 
packing ring 67 of the feed- valve piston 74- should be cleaned 
without removing, and then oiled a little. In putting the parts 
together, do not screw the nuts that fasten the rotary-valve 
handle too tight; and, in screwing the lower casing 69 of the 
feed-valve attachment on the F-(5 valve, be sure that there is an 
opening of about -£% of an inch between the upper and lower 
parts of governor body, since screwing the lower part up tight 
crushes the gasket, as already explained. 



48 THE AIR BRAKE. §2 



THE EQUALIZING RESERVOIR. 



ITS IMPORTANCE. 

71. The equalizing reservoir plays a very important part in 
the handling of the brakes in service applications. The duty 
of this reservoir, as explained in Art, 75, Part 1, is to increase 
the capacity of chamber D in the brake valve an amount suf- 
ficient to enable small service reductions to be made, so as to 
apply the brakes gradually. 



EFFECTS OF LEAKS. 

72. Slight Leaks. — A slight leak in the equalizing reser- 
voir or its connections constantly tends to reduce the pressure 
in chamber D; the effect of such a leak depends on the position 
of the brake- valve handle. 

In full-release and running positions there would practically 
be no effect, aside from the fact that a little extra air would 
have to be supplied by the pump. 

When the valve is moved to service position, the leak acts to 
help the reduction made by the engineer, and, consequently, 
a harder application of the brakes than is intended will be 
made. 

When the valve is moved to lap position, the leak continues 
to reduce the pressure in chamber D; train-pipe pressure then 
raises the equalizing piston and escapes to the atmosphere, and 
this sets the brakes harder. A slight leak from the equalizing 
reservoir, therefore, causes a blow from the train-pipe exhaust 
valve when the brake valve is in lap position, and the longer 
the train pipe, the stronger the blow will be. 

73. Bad Leaks. — A bad leak, such as would be produced 
by a split or broken pipe to the equalizing reservoir or air 
gauge, will allow chamber D pressure to escape entirely, and 
the train-pipe exhaust valve will be held open by train-pipe 
pressure until it has all escaped. This will result in a full 
application, or, in some cases, an emergency application of the 



§2 THE AIR BRAKE. 49 

brakes. Such a leak, therefore, will render the brake system 
useless until it is stopped. 

Leak in Equalizing Reservoir. — If the leak occurs in the equal- 
izing reservoir, or in the pipe leading to it, place a blind gasket 
in the union at T of the brake valve, Figs. 14 and 16, plug the 
train-pipe exhaust elbow 25 (which is threaded for this pur- 
pose), and then use the brake valve carefully in emergency 
position (like the old three-way cock) in making service stops. 
In all other respects, the brake valve should be operated as 
usual, since placing the gasket and plug in the places men- 
tioned does not affect its working in release, lap, running, or 
emergency positions. *•'■-. 

Defective Gauge Pipe. — If the leak is due to a split or break 
in the pipe leading to the air gauge, the trouble may be 
remedied by putting a blind gasket in the union W of the 
brake valve. This will cut out the black hand of the gauge, 
but will not in any way affect the working of the brake valve. 

It is an interesting experiment to put a blind gasket in the 
union T, where the pipe from the equalizing reservoir connects 
with the brake valve, arid notice the effect of a service reduc- 
tion when the engine is connected, first to a train of seven cars 
or less, and then to a train of considerably more than seven. 



MAKING SERVICE STOPS PROM EMERGENCY POSITION. 

74. Considerable care and judgment must be exercised in 
making service stops from emergency position. If the exhaust 
port is opened too ivide, or opened or closed too rapidly, trouble 
is almost sure to follow. The exhaust port should be opened 
very gradually and just sufficiently wide to make, as nearly as 
possible, the usual train-pipe reduction; if opened wider, too 
great a reduction will be made and rough handling of passen- 
gers or freight will probably result. 

Opening Exhaust Port Too Rapidly. — If the exhaust port is 
opened too wide or too rapidly, a quick reduction is made 
in the forward end of the train line, which may operate the 
emergency part of the triple — if it does not, it sets the front-end 



50 THE AIR BRAKE. §2 

brakes before the back-end ones; and the longer the train pipe, 
the greater this effect will be. This tends to retard the front 
cars, and the rear ones, which are not retarded, crash into them 
with great force if the train is very long, and damaged draft- 
rigging or freight is the result. 

Closing Exhaust Port Too Rapidly. — If the exhaust port is 
closed too quickly, the forward brakes may be "kicked off." 
When once in motion, the long column of air in the train pipe 
cannot be stopped instantly; consequently, if the exhaust port 
is closed very rapidly, the air will continue to flow forwards 
after it is closed and may raise the pressure in the front end of 
the train pipe sufficiently to release or kick off the forward 
brakes. If the exhaust port is closed so quickly that the train- 
pipe pressure is not equalized the whole length, the triple valves 
on the front end will equalize the auxiliaries and train pipe at a 
lower pressure than on the rear cars, and, when the train-pipe 
pressure finally equalizes the whole length, the pressure in the 
train pipe on the head cars will be greater than in the auxili- 
aries on those cars, thus causing the triples to move to release 
position and release some of the head brakes. 



The Air Brake 

(PART 3.) 



OPERATING AND TESTING. 



THE MAKE-UP OF A TRAIN. 

1. The smoothness and ease with which a freight train can 
be handled, as well as the facility with which it can be stopped 
by means of the air brake, depends, to a considerable extent, on 
the way the train is made up. The make-up of a passenger 
train, on the other hand, affects the handling of the train 
so very slightly that, so far as the braking is concerned, no 
particular attention need be paid to it. 



GENERAL CONSIDERATIONS. 

2. The conditions of braking on passenger and freight trains 
differ greatly. On a passenger train there is no free slack 
between cars to bother us; both the load and the braking 
power are distributed quite uniformly throughout the length of 
the train; the brakes are kept in good condition and the piston 
travel maintained within proper limits; train-pipe, auxiliary, 
and brake-cylinder leakage is very slight; and the length of the 
train pipe is such that, practically, the brakes set simultane- 
ously on all parts of the train. 

With a freight train, on the other hand, there is a great deal 
of slack, which must be handled properly to avoid severe 
shocks; the load is generally distributed unevenly throughout 
the train ; the brakes generally do not receive sufficient attention 

n 



THE AIR BRAKE. §3 



to keep them in as good condition as those on a passenger 
train; and the brake-piston travel is seldom uniform. Conse- 
quently, the braking force, even on an all- air train, is not 
uniform throughout its length ; the leakage in the brake system 
is greater in freight than in passenger service; and, lastly, the 
train pipe on a freight train is generally so long that the retard- 
ing effect of friction on the flow of air through it is sufficient to 
cause an appreciable interval of time to elapse between the 
operation of the first and last brakes. The increased diameter 
of the freight-car train pipe helps this last trouble in a measure. 

3. Effects of Slack. — There is always a great deal of free 
slack in a freight train, and it must be handled with great care 
or else severe shocks will result, which may injure both draw- 
bars and freight. The slack is less troublesome on all- air than 
on part-air trains, since in the former each car is equipped with 
the air brake, which permits of the retarding force being applied 
to, or removed from, each car at nearly the same instant; the 
slack, therefore, cannot gather or run out quickly, and shocks 
when they occur are less severe. However, a large number of 
freight trains are in operation that have only a part of the cars 
equipped with air brakes, and with these the effect of slack 
is most severe. 

The engineer has more or less direct control over the slack 
that is between the air cars, but he has no control over that 
between the non-air cars; consequently, the free slack back 
of the air cars must be * ' taken up ' ' every time the brakes are 
applied, and be run out at every release. Whether a shock will 
occur either in "bunching" or "stretching" a train, depends on 
how quickly it is accomplished. If the first service reduction is 
made sufficiently heavy to bunch the train quickly, the last cars 
will run up against the others with great force; and the heavier 
the last cars are loaded, the greater will be the shock and con- 
sequent damage. On the other hand, the lighter the rear cars, 
the less the shock will be; hence, a part-air train can be handled 
more easily and with less chance of damage to freight if 
the heavily loaded cars are placed next to the air cars, and the 
less heavily loaded ones and empties next to the way car. 



THE AIR BRAKE. 



4. Effects of Unevenly Distributed Eoad. — When a 
freight train is made up of both loaded and empty cars, and the 
loaded cars are distributed haphazard throughout the train, 
the load is said to be distributed unevenly. Since it is harder 
both to start and stop loaded cars, shocks of a more or less 
serious nature occur at different points of the train every time it 
is started, stopped, or has its speed retarded suddenly. This 
trouble can be avoided by placing all loaded cars together at 
the head end of the train. 

5. Effects of Unequal Piston Travel. — To effect 
smooth handling of freight trains by means of the air brake, it 
is essential that the travel of the brake-cylinder pistons be kept 
within the proper limits. If the piston travel on some of the 
cars in a train is too short, while on others it is too long, shocks 
will occur at a number of points in the train every time the 
brakes are applied or released. This is due to the fact that 
the brake cylinders having a short piston travel apply their 
brakes harder at each reduction and equalize with their auxili- 
aries sooner, and at a higher pressure, than those having a 
long piston travel; also, they release later than the long-travel 
brakes. This causes the slack to be gathered at some parts 
of the train, and to run out at others, every time the brakes 
are applied or released, producing a surging of the cars 
that results in shocks, which make smooth handling of the 
train difficult. 

6. Effects of Eength of Train Pipe. — The length of 
train pipe also has considerable influence on the ease with 
which the train can be handled. Frictional resistance tends to 
retard the flow of air through the train pipe, and the longer the 
train pipe the more troublesome this retarding effect becomes. 
When conditions are normal, the retarding effect is such that in 
making an ordinary service reduction on a fifty-car air freight 
train, the pressure in the head end of the train pipe is reduced 
about 6 pounds before the reduction begins to be felt at the 
rear end; while, on releasing brakes on such a train, there may 
be a difference of pressure of about 10 or 12 pounds between the 



THE AIR BRAKE. §3 



two ends, the pressure at the head end being the higher. This 
difference of pressure causes the head-end brakes to both apply 
and release sooner than the rear-end ones, with the result that, 
on a long train, some severe shocks will be produced if the 
brakes are not handled with skill and judgment. 



MAKING UP FREIGHT TRAINS. 



ALL-AIR TRAIN. 

7. All-air trains can be handled much more smoothly 
and satisfactorily if all the loaded cars are placed next 
to the engine, and the empties next to the way car. Also, 
when the cars are mostly equipped with quick-action triples, 
care should be taken not to place two or three cars together 
that either have plain triples, or have their brakes cut out, or 
are merely piped, since, in cases of emergency, it will be 
impossible to obtain the quick action of the triples back of them. 



PART-AIR TRAIN. 

8*. In making up a part-air train, all the air cars, whether 
loaded or empty, should be placed together at the head end of 
the train and cut into service. Every air brake possible should 
be employed in braking, since the more in use the more 
smoothly the train can be handled; besides, they may be 
needed to make a quick stop in an emergency. Do not place 
together three or four cars with plain triples, or with brakes cut 
out, if most of the cars have quick-action triples, but distribute 
them among the quick-action cars. As to the non-air cars, the 
best results will be obtained if they can be so arranged that the 
loaded ones are next to the air cars and ahead of the empties. 
Empty non-air flat cars are liable to be damaged if placed 
ahead of loads next to the air cars; they should come next 
to rear end. 



§3 THE AIR BRAKE. 



TESTING BRAKES. 



ENGINE EQUIPMENT. 

9. The Air Fump. — Any defects in the engine air-brake 
or signal apparatus should be reported at the end of the trip, 
so that the necessary repairs can be made before the engine 
is again called into service. If necessary, tests should be made 
to locate the defects. 

The air pump should be tested under its usual head of steam, 
as follows: With the pump running at normal speed, note the 
time at intervals of 10 pounds, while the main-reservoir pres- 
sure is being raised from 40 to 90 pounds. If the pressure is 
pumped in the usual time, during which the pump shows no 
sign of disorder, the presumption is that it is in good condition 
and no further tests will be necessary. If, on the other hand, 
the test shows that the pump is not in its normal condition, 
the trouble may be due to leaky piston packing-rings, to leaky 
receiving valves, to back leakage from main reservoir, or to the 
air valves being stuck. Tests, as in Art. 13, Part 2, should 
be made to locate the cause. 

10. The Pump Governor. — The governor should be 
tested to see whether standard pressure is obtained when it 
stops the pump; also, to see whether it will start the pump 
promptly when a light reduction of not more than 2 pounds is 
made in the pressure that operates the governor (see Art. 28, 
Part 1). If the pump stops either before or after standard 
pressure is obtained, the governor should be adjusted, by means 
of the regulating nut £0, until it regulates the pump properly 
(see Art. 57, Part 2). If the governor does not start the pump 
promptly when a slight reduction is made, it may be due to a 
leaky pin valve, to the relief port c being stopped up, or (in 
governors not having this relief port) to the governor piston 
packing rings being too tight (see Art. 2, Part 2). - 

11. The Brake Valve. — The brake valve should first be 
tested for leaks from main reservoir into the train pipe. In the 
D-8 valve this would occur past the rotary valve, so that a test 



6 THE AIR BRAKE. §3 

for a leaky rotary should be made by one of the methods given 
in Art. 45, Part 2. In the F-6 valve, the leak may occur either 
past the rotary valve or the gasket 32. Tests for these defects 
are given in Arts. 60 and 61, Part 2. Next, if the valve is of 
the D-8 type, the excess-pressure spring should be tested to 
ascertain if it is of the proper resistance, as in Art. 43, Part 2; 
or, if the valve is of the F-6 type, test the tension of the regu- 
lating spring 68 in the feed- valve, as in Art. 58, Part 2. Then, 
if a D-8 valve, test for a leak past the excess-pressure valve, 
Art. 49, Part 2; or, if an F-6 valve, test for a leaky supply 
valve and leaky feed-valve case gasket, Arts. 62 and 65, Part 2. 
Next make a service reduction of 20 pounds in chamber D, 
and note the time required for the reduction. If it takes longer 
than 5 seconds, the indications are that the size of the passage 
in the preliminary- exhaust port is reduced; or the piston pack- 
ing-ring is worn; or, in the F-6 valve, the gasket 32 is leaking 
(see Arts. 53 and 67, Part 2). If the reduction is made in 
much less time than 5 seconds, it indicates either that the 
equalizing reservoir leaks, or that there is water in it. For a 
test for leaks in the equalizing reservoir, see Art. 72, Part 2. 

12. Driver and Tender Brakes. — An air gauge should 
be attached to the driver- and tender-brake cylinders at least 
once a month, to ascertain the condition of the piston packing 
leathers. After the auxiliaries are fully charged, make a 35- or 
40-pound service reduction, lap the valve, and note the pressure 
at which the auxiliary and brake cylinders equalize. Also, note 
the pressure at the end of 5 minutes; if it does not decrease 
more than 5 or 6 pounds during that time, the brake cylinder 
is in good condition. If the gauge shows that the brake- 
cylinder pressure decreases at a considerably greater rate, 
examine the packing leathers and look for leaks in the cylinder 
connections, the gasket between the cylinder and head, and the 
piston-rod packing. 

If the driver- brake cylinder is in such a position that it is 
subjected to considerable heat, it should be oiled sufficiently 
often to keep the packing leather soft and pliable. It is poor 
practice to use water to soften the packing leather, since it dries 



§3 THE AIR BRAKE. 



out very quickly and the leather then becomes harder and is 
much more liable to crack. 

Driver Brake Fails to Apply. — If the driver brake fails to 
apply, first see whether the handle of the cut-out cock is turned 
so as to cut out the brake. The brake being cut in, open the 
release cock on the auxiliary to see whether it is charged. 
If the discharge indicates that the auxiliary is charged, it may 
be that the triple piston, being badly gummed, is stuck in the 
release position, or that its packing ring is badly worn. In 
either case, when a reduction is made, the auxiliary may 
equalize with the train pipe through the feed groove and past 
the packing ring so fast that the piston is not moved out. 
In case the triple piston is stuck, one or two sudden heavy 
reductions should loosen it. If the cause cannot be located, 
take down the triple and examine it. Also, examine the brake- 
cylinder packing leathers, as a leak there is a cause for failure 
to apply. 

Driver Brake Fails to Release. — This may be due to a worn 
piston packing-ring in the triple valve, aided by dirt and gum, 
theleakage past the packing ring allowing auxiliary pressure to 
equalize with the train line without moving the triple piston; 
or the triple exhaust port maj^ be stopped up; or the release 
spring in the brake cylinder may be weak or broken; or, in 
the cam brake, the piston travel may be so long that the brakes 
lock against the drivers. In the latter event, the cams must be 
pried until the brake releases. In the event of the brake being 
stuck, try to release it by making a heavy reduction and then 
quickly placing the brake valve in full-release position. 

Driver Brake Releases. — If the driver brakes release soon after 
being applied, it may be due to a leak in the auxiliary reservoir 
or its connections, to a leaky graduating valve in the triple 
valve, or to a leak in the piston packing leather or piston-rod 
packing. See also, Art. 74, Part 2. 

13. Triple Valves. — Plain triples are used on the engine 
and tender; therefore, if a blow occurs at the exhaust port of 
either triple, look for a leaky slide valve 3, or for a leak past the 
plug cock 13 into port/, Fig. 7, Part 1. To determine which of 



8 THE AIR BRAKE. §3 

these is causing the blow, apply the brake lightly; this causes 
the slide valve to close communication between port / and the 
exhaust port k, and if the trouble is due to a leaky plug cock, 
the blow will cease, while if due to a leaky slide valve, it will 
continue. 

The method of testing the air-signal system for defects will be 
given after the signal system has been explained. 



TERMINAL TEST OF TRAIN. 

14. General Instructions. — If possible, all the air cars 

should be coupled up and the brakes cut in before the engine is 
connected to the train, as both time and air can be saved by 
so doing. 

On taking his engine, the engineer should start his pump and 
run it slowly until sufficient pressure is accumulated in the 
main reservoir to properly cushion the pump; he should then 
increase its speed and pump up the proper main-reservoir 
pressure. Also, he should carefully inspect the air-brake 
apparatus on both the engine and tender, to assure himself that 
all necessary repairs have been made, and that everything is in 
perfect working order. The train pipe on the engine should be 
blown out to get rid of any dirt and water there may be in it 
before the engine is coupled to the train. The brake valve 
should be carried in lap position* while the engine is being 
coupled to the train. After coupling the hose between engine 
and tender, the tender angle cock should be opened first, so 
that the hose will be charged when the car angle cock is opened. 
If the car angle cock is opened first and the train is short and 
equipped with quick-action triples, the brakes are liable to 
apply quick-action, due to the sudden reduction caused by 
train-pipe air expanding to fill the empty hose. The angle 
cocks should always be opened slowly, since, if the handle is 
turned quickly, emergency action may result. 



* There is considerable difference of opinion as to the position in 
which the valve should be carried when coupling to the train, but the 
consensus of opinion seems to favor lap position. 



§3 THE AIR BRAKE. 



During the time the train is being charged, the inspector, or 
trainman, should pass along and examine each car for leaks 
and other defects. It should be observed whether all of the 
angle cocks are open, except the last one on the rear air-braked 
car; whether the cock in each branch pipe is open so that all of 
the cars, except those that are not in good condition, are cut in; 
whether the hand-brakes are fully released; and, if the retainers 
are to be used, whether the retainer handles are turned up. 

After the train has been fully charged to standard pressure, 
the brake system should be tested. If time will permit, 70 
pounds pressure should always be obtained before this test is 
made; but in no case should it be made with less than 60 
pounds for passenger trains or 50 pounds for freight trains. 
When the train is fully charged, it will be indicated by the 
pump slowing up. 

To make the test, a service reduction of from 5 to 7 pounds, 
or one just sufficient to move the brake pistons out past the 
leakage grooves, should be made, and the brake valve lapped. 
The engineer should then watch the air gauge to ascertain the 
extent of train-pipe leaks, since they will be indicated by the 
black* hand falling. A sufficient number of moderate service 
reductions should then be made to produce a 20-pound train- 
pipe reduction, and the brakes should then be held on while the 
train is inspected to see whether all brakes set or whether any 
of them leak off after being set; also, the length of the piston 
travel on each car should be examined. After the entire train 
has been inspected, the engineer should be signaled to release 
brakes, and, if the train is equipped with the air-signal system, 
the signal should be given from the rear car to make sure that 
the air signal is connected up and working properly. The 
engineer should then release the brakes, and, if the retainers 
were not in use, the train should again be inspected to see 
whether all brakes release properly and whether there is a blow 
at the exhaust port of any of the triple valves. If the retainer 
handles Avere turned up during the test, the inspector or brake- 
man should go over the train after the engineer has released, and 



*The train-line hand on the new semaphore gauge is white. 



10 THE AIR BRAKE. §3 

turn the retainer handles down, noting, as he turns each down, 
whether the brake releases, and whether a blow occurs at retainer 
after brake has released. If air discharges from the retainer as 
the handle is turned down, the retainer is working properly. 
After the test, a report should be made to both the engineer and 
conductor, showing the total number of air and non-air cars in 
the train; the number of air cars in good working order and the 
number cut out; the condition of the piston travel; the number 
of retainers, if they are to be used, that are working properly; 
and also, the general condition of the train. 

In making the first service reduction in testing the brakes, 
the engineer should note the length of time the train-pipe 
exhaust blows, as by making a practice of so doing, he soon 
will be able to judge of the length of train pipe that is cut in, 
and thus, in many instances, can detect an angle cock that has 
been left closed. He should also note if the sound of the train- 
pipe exhaust is full and continuous, or strong at first and then 
stringing out weak for some seconds; a little practice will teach 
him to distinguish the effect of a partly opened angle cock or a 
stoppage in the train pipe: 

15. Brake Falls to Apply. — If, during the inspection, a 
brake is found that will not set, first make sure that it is cut 
in, and then try the bleed cock on the auxiliary reservoir, to 
ascertain whether the reservoir has been charged. If the 
auxiliary is not charged, and there is sufficient time at disposal, 
take the triple down and look for a stopped-up feed groove. 
If air issues freely from the bleed cock, it may be that the feed 
groove was only partially stopped up, resulting in the auxiliary 
being charged insufficiently to set the brake when the test was 
made. If the trouble cannot be remedied at the time, cut 
out the brake by closing the cut-out cock in the branch pipe 
leading to the triple. 

16. Brake Releases. — If a certain brake will not stay 

on, but releases as soon as it is set, the trouble is due to a heavy 
leak either from the brake cylinder or from the auxiliary 
reservoir. If the leak is from the auxiliary, the triple valve 
will move to release position, and air from the brake cylinder 



§3 THE AIR BRAKE. 11 

will come out of the exhaust. If the leak is in the brake 
cylinder only, the triple valve will not move. The leak from 
the brake cylinder may occur through the leakage groove or 
past the piston in the brake cylinder. The hand-brake may be 
partly set, or the slack in the brake may be taken up so short 
that the brake-cylinder piston cannot move out far enough to 
cover the leakage groove, in which case the brake will either 
not set, or will release at once. The leak past the brake- 
cylinder piston may be due to a dried-out packing leather, or to 
the expander ring being out of place. 

Leaks from the auxiliary reservoir may occur through a 
defect in the release valve (Art. 34, Part 2) or through the triple 
exhaust port (Arts. 25 and 27, Part 2). If at the release 
valve, look for a bent valve rod or for dirt on the valve seat. 
A leak due to the former may be remedied by straightening 
the valve rod; that due to the latter can in some cases be 
remedied by quickly jerking the release valve open two or 
three times. If the leak cannot be stopped, the brake must 
be cut out. 

17. Brake Fails to Release. — If a brake fails to 
release, and there is a strong blow at the exhaust port of the 
triple valve, the trouble is caused by a bad leak past the rubber 
seat of the emergency valve, or else the valve is stuck open 
(see Art. 27, Part 2). In either case, train-pipe air enters the 
brake cylinder at a faster rate than brake-cylinder air can 
escape through the exhaust port, and consequently pressure 
accumulates in the cylinder and holds the brake on. If the 
trouble does not cease when the triple is jarred lightly with a 
piece of wood, make a quick, heavy reduction, and then release; 
if this does not prove effective, cut out the brake by closing the 
cut-out cock, drain the auxiliary reservoir by means of the 
release valve, and then cut the brake in suddenly. If the blow 
still continues, cut the brake out of service. 

If, when the brake refuses to release, there is no blow at the 
triple exhaust, first see if the handle of the retainer on that car 
is turned down, and, if so, whether the retainer exhaust port is 
stopped up. A certain. kind of wasp has been known, in some 



12 THE AIR BRAKE. §3 

localities, to build its nest in the retainer and thus plug it up. 
The retainer being all right, see whether the hand-brake is fully 
released; whether the slack has been taken up too tight; or 
whether the brake has released, but the spring in the brake 
cylinder been unable to move the brake piston to release 
position. If the trouble is not in any of these places, it is 
pretty sure to be due to a badly worn packing ring in the 
triple piston. 

Testing Triple Piston. — The condition of the triple piston 
packing ring can be determined as follows: Apply the brake 
by making a 10- or 12-pound reduction, and then gradually 
open the release valve on the auxiliary of the defective brake 
a very small amount, so that a slight discharge takes place 
through it. If the brake does not release within 10 or 15 
seconds, gradually open the release valve a little wider, so as to 
increase the rate of discharge. Continue to increase the dis- 
charge every 10 or 15 seconds until the brake releases; then 
the rate at which air is escaping through the release valve will 
be a measure of the rate at which train-pipe air escapes past 
the triple piston packing ring. The escape of air through the 
release valve, however, must be slightly greater than that past 
the packing ring, as otherwise a sufficient auxiliary reduction 
could not be obtained to release the brake. When the packing 
ring is worn, a rather quick, heavy reduction of auxiliary 
pressure is necessary to move the triple to release position; in 
such a case, therefore, the brakes are more liable to stick on 
a long, than on a short, train. 

If the engineer finds that some of the brakes have a tendency 
to stick, he should carry the full amount of excess pressure all 
the time, and, at places where a heavy application must be 
made, he should have a high main-reservoir pressure to insure 
a prompt release. 

18. Train-Pipe I^eaks. — In inspecting a train for leaks, 
the parts to be inspected may be divided into: (1) the train 
pipe and its branch pipes; (2) the hose and couplings; 
(3) the triple valves; (4) the auxiliary reservoir; and (5) the 
brake cylinder. 



§3 THE AIR BRAKE. 13 

1. The Train Pipe and Branch Pipes. — Leaks in the train 
pipe may occur at any of the joints. If at the union joint at 
the car drain cup, it can sometimes be stopped by tightening 
that joint; if not, a new gasket must be used. When the leak 
occurs at the joint where the branch pipe screws into the car 
drain cup, or in the joints at the stop-cock in the branch pipe, 
it can sometimes be stopped by disconnecting the branch pipe 
at the triple valve and turning the pipe until the leak ceases. 
If the leak occurs in the union at the triple, it may be stopped 
by tightening the union joint or by replacing the union gasket. 

The leak may be due to a split or break in the train pipe. 
In that case, switch the car behind all of the air cars and couple 
its hose to that of the last air car; then close the front angle 
cock on the defective car and open the rear one on the car 
ahead, so that the hose will be included in the train pipe. 
Then, should the train part between the defective car and the 
last air car, the brakes will be applied. 

2. The Hose and Couplings. — In looking for leaks in an air- 
brake hose, not only the hose but also the couplings and 
nipples should be examined. The hose itself may be porous, 
in which case the air escapes so silently and in such finely 
divided streams that it is very liable to be overlooked, especially 
as the hose ma}' have the appearance of being perfectly sound. 
In some cases, such a hose can be detected by bringing a lighted 
torch near it, or by wetting the hand and moving it over the 
hose, the escaping air making the hand feel cooler. The best 
method, however, is to apply a little soap and water by means 
of a sponge or piece of waste; the escaping air will be indicated 
by the formation of bubbles. Such a hose, when located, 
should be removed and marked "defective," a sound hose 
being put in to replace it. 

Leakage at the hose coupling may occur past the gaskets 2 S 
or under the hose clamps c, Fig. 11, Part 1. If in the gaskets, 
close the angle cocks on either side of the hose, separate it, and 
if the gaskets have been distorted out of shape, straighten them 
out and try them again. If they still leak, new gaskets shouM 
be used. If none are at hand, separate the couplings and put a 
match or small sliver of wood back of each lug and again unite 



14 THE AIR BRAKE. §3 

the couplings. This will force the gaskets closer together, and 
will probably stop the leak. Sometimes the manner in which 
frozen couplings are parted is the cause of trouble with coupling 
gaskets. Frozen couplings should always be thawed out 
before an attempt is made to part them, as otherwise the gaskets 
are almost sure to be ruined. Paper should never be used 
between the hose gaskets to stop a leak, as it is very liable to 
work into the brake system and cause trouble. If the leak is 
under the hose clamp c and. cannot be remedied by tightening 
the clamp, a new hose must be substituted. 

Leakage at the hose nipple may be due to the- nipple not 
being screwed into the angle cock tight enough, or the leak may 
occur under the nipple hose clamp. If the former, screw up 
the nipple until it makes a tight joint; if the latter, tighten the 
clamp, and if this does not stop the leak, change the hose. 

3. The Triple Valves.— A blow at the triple exhaust port 
may be due to a leak either from the train line or from the 
auxiliary reservoir. To test for the source of the blow, close 
the stop-cock in the branch pipe so as to cut out the brake: 
if the leak is from the train line, the brake will set; if from the 
auxiliary reservoir, it will not. The exhaust port of the triple 
valve or of the pressure retainer must never be plugged up on 
account of a blow occurring at either place, for the reason that 
it would then be impossible to release the brake on that car. 

4. The Auxiliary Reservoir. — Leakage from the auxiliary 
reservoir may occur through either the release valve or the 
triple exhaust port, as already mentioned. 

5. The Brake Cylinder. — Brake- cylinder leakage was discussed 
in Art. 35, Part 2. If the leakage is very great, the brake 
should be cut out of service. 

19. Cutting Ont a Brake. — When, on account of some 
defect in the apparatus, it becomes absolutely necessary to cut 
a brake out of service, proceed as follows: If a quick-action 
brake, close the cut-out cock in the branch pipe of the triple 
valve; if a plain triple is used, first release the brake so that 
the brake piston moves back and uncovers the leakage groove, 
turn the handle 15 (Fig. 7, Part 1) to the position 15 f , that is, 



§3 THE AIR BRAKE. 15 

midway between the horizontal and vertical positions. The 
release valve of the auxiliary reservoir must then be opened and 
secured in that position, if a freight car, so that the reservoir 
will be relieved of all pressure; otherwise the brake is liable to 
set and cause trouble. Never attempt to cut out a brake by 
closing the angle cocks at the ends of the car, as that will not 
only cut out the brake on that car, but on all others back of it, 
since closing an angle cock cuts off the train pipe back of it. 

20. Cutting Out a Car. — A brake is cut out by closing 
the stop-cock in the branch pipe. A car is cut out by 
closing the angle cocks at each end of the car, the release 
valve being opened the same as when a brake is cut out. After 
a car has been cut out, it should be switched to the rear of 
the air cars, and its front hose coupled into the train pipe for 
the reasons just given in Art. 18, 1. 



RUNNING TEST. 

21. A running test of the brakes should be made on all 
trains when leaving the terminal station, to make sure that the 
brakes set and release properly throughout the train. A run- 
ning test should also be made when, for any reason, a train 
is parted during the run. 

The engine throttle valve is kept open while this test is being 
made, the engineer simply making a light service reduction to 
see whether, and how well, the brakes take hold. As soon as 
he feels them take hold properly, he releases. While making 
the reduction, the engineer should note the length of time the 
train pipe exhausts, since by so doing he can judge of the length 
of the train pipe that is cut into service. 



TEMPERATURE TEST. 

22. It is well known that the holding power of the brakes 
varies greatly on different cars, due to defects in the brake 
system. It is well known, also, that if a brake is applied to a 
revolving wheel for any length of time, the wheel will become 
heated; and the longer the brake is held on, or the greater the 



16 THE AIR BRAKE. §3 

retarding force exerted by it, the greater will be the resulting 
temperature of the wheel. Of course, the brakes on a train are 
all applied at the same time, so that if they held equally well 
the wheels would be of a uniform temperature throughout the 
train, and no information could result from a test of the wheel 
temperature. It will be found, however, that the wheels heat 
unequally, some being much hotter and others much cooler than 
the average. If the brakes on the wheels of average temperature 
are assumed to be doing their proper share of work, those on 
the wheels of higher temperature must, for some reason, be 
doing more than their share, while those on the wheels of lower 
temperature must be doing less than their share; hence, a test 
and record of the temperature of the wheels of a train, after the 
brakes have been applied for some time — as in descending a long 
grade — will give some very interesting and useful information 
as to the condition and relative holding power of the brakes on 
different cars. The record should be such that it will show 
clearly which brakes require attention, and therefore should 
contain a statement of the number of each car on which the 
temperature of the wheels is very much above or below the 
average, and whether the wheels are too hot or too cold. 

23. Locating Defects. — Having, then, a record of the 
defective brakes, stating the comparative temperatures of the 
wheels, it remains to locate and remedy the defect that causes 
the trouble. 

If the wheels on a certain car are too hot, it indicates either 
that the brake on that car holds better than the other brakes or 
else it did not fully release with the others, and, consequently, 
had been dragging. Hence, the piston travel on that car 
should be measured to see whether it is too short, and the 
hand-brake inspected to see whether it is fully released. 
Also, inspect the pressure retainer to see whether it is working 
properly, and the brake cylinder to see whether the piston is 
stuck out, due to a defect in the cylinder or brake rigging. 
The brake may have been held on, due to a leak from the train 
pipe into the cylinder past the emergency valve, but this would 
be at once detected by a blow at the triple exhaust port. 



§3 THE AIR BRAKE. 17 

If the wheels are too cold, it indicates either that the brake, 
for some reason, did not hold as well as the others, or did not 
apply with the others, or else that it released soon after it was 
set. The brake-piston travel, therefore, should be measured to 
see whether it is too long — in which case the force exerted by 
the brake would be considerably less than with the proper 
piston travel; or whether it is too short — in which case it is 
possible that the brake piston does not cover the leakage groove, 
the brake leaking off as a result. Also, the brake may not 
have applied at all, as the cut-out cock may not have been 
opened; or else it may have released again, due to leakage in 
the brake cylinder, auxiliary reservoir, triple valve, or — when 
the brakes have been released and the retainer is supposed 
to be holding 15 pounds in the brake cylinder — in the pipe 
leading to the retaining valve. 

On roads where there are long down grades on which the 
retainers must be used, the wheel-temperature test is especially 
essential. When the brakes are held on for a considerable 
length of time, some of the wheels are liable to become very 
hot, and since the heating takes place at the rim, the wheel 
is subjected to stresses that are liable to cause it to break. 



HANDLING TRAINS. 



SERVICE STOPS. 

24. General Considerations. — In making a service 
application of the brakes, the amount of the first reduction 
will depend somewhat on the length of the train. Whatever 
the length of the train pip.e, the first reduction must be suf- 
ficient to cause the brake-cylinder pistons to move out far 
enough to cover the leakage grooves; otherwise, the brake will 
not set, and the air that should have been used in setting it 
will pass out through the leakage groove and be wasted. If 
too heavy a reduction is made, the slack of the train (if a 
freight) will run in so quickly that a severe shock will result. 



18 THE AIR BRAKE. §3 

The amount of reduction necessary to cover the leakage 
grooves can readily be determined when testing the train or 
when making the first stops. In passenger service, from 5 to 7 
pounds is generally sufficient for the first reduction. With a 
freight train consisting of, or controlled by, ten air cars, a 
reduction of from 5 to 7 pounds will give good results. When 
the train contains more than this number of air cars, the reduc- 
tion must be increased accordingly. For example, a train 
containing twenty-five air cars will probably require an 8-pound 
initial reduction, while a train of fifty or sixty air cars may 
require a 10-pound reduction. 

25. Tlie First Reduction. — There are several reasons 
why a heavier first reduction is necessary with a long train 
than with a short one. Of course, since the volume of air con- 
tained in the equalizing reservoir is constant, regardless of the 
length of the train line, a reduction of chamber D pressure (of 
any given amount) can always be made in practically the same 
time. The volume of air in the train line, on the other hand, 
increases directly with its length, so that the longer it is, the 
more time is required to make a given reduction in the train- 
pipe pressure. Now, since train- pipe pressure reduces more 
slowly on a long train than on a short one, there is a greater 
chance for auxiliary pressure to feed back into the train pipe 
through the feed groove before it is closed by the triple piston. 
This reduces auxiliary pressure and has the same effect as 
though the first reduction had been lighter. Then again, the 
slower the train-pipe pressure is reduced, the slower will the 
auxiliary pressure feed into the brake cylinder, and, conse- 
quently, the more air will leak out of the leakage groove and 
past the packing leather. 

The amount of the reduction depends, also, on the fit of the 
equalizing piston packing ring in the brake valve. This ring 
never makes an air-tight fit, and in some cases considerable air 
can leak by it. Now, when the train is long, a reduction can be 
made several seconds sooner in chamber D and the equalizing 
reservoir than in the train pipe; hence, chamber D pressure 
may be less than train- pipe pressure for several seconds during 



§3 THE AIR BRAKE. 19 



a service reduction. In consequence of this, air will leak back 
from the train pipe into chamber D and raise chamber D pres- 
sure, and the longer it takes for the train pipe to reduce, or the 
more the piston packing-ring leaks, the more will chamber D 
pressure be raised. Thus, what is intended for a 6- or 7-pound 
train-pipe reduction may result in only a 4- or 5-pound reduc- 
tion, and in order to get the 6- or 7-pound train-pipe reduction 
in such a case, a reduction of 8 or 9 pounds may be necessary. 

26. Reductions Following. — The amount of the reduc- 
tions after the first reduction depends somewhat on the 
length of the train pipe and the condition of the brake appa- 
ratus. With the apparatus in good condition the reductions 
should not, as a rule, be more than from 2 to 6 pounds, being 
small when the train pipe is short, and increasing as the 
length of the train pipe increases. 

Experiment has shown that a brake grips the wheel better, 
and, consequently, retards the train more, at slow than at fast 
speeds for the same train-pipe reduction; therefore, the danger 
of producing shocks is greatest at slow speeds, and the reduc- 
tions should be made accordingly. Also, sufficient time must 
elapse between reductions to allow all of the brakes to set and 
the slack to equalize throughout the train. If the reductions 
are made too close together, the effect will be the same as 
though one heavy reduction had been made. For example, if 
one 3-pound reduction is followed by another before the train- 
pipe exhaust ceases, the brakes will set as though a 6-pound 
reduction had been made. It must be remembered that the 
graduating valve in the triple valve does not close until the 
train-pipe exhaust ceases, regardless of when the preliminary 
exhaust stops, and any reduction made before it closes will 
prevent that event taking place until auxiliary pressure is 
reduced an amount equal to the sum of the reductions. 

27. Number of Reductions. — The number of reduc- 
tions to be made in a service application depends on circum- 
stances. It is not good practice to wait so long before applying 
the brakes that a sufficient number of heavy reductions must 
be made to cause a full application, in order to make the stop 



20 THE AIR BRAKE. §3 



at the proper spot. It is better to make the first reduction at 
such a distance from the stopping point that a full application 
of the brakes will not be necessary. The reductions should be 
moderate and sufficient in number to make not more than a 
15-pound train-pipe reduction in bringing the train to a stand- 
still. The engineer then has at his command a reserve bra- 
king force that will be of the greatest value in case of emergency 
while running into a station. 

28. Passenger-Train Stops. — An ordinary station stop 

with a passenger train is generally made with one application of 
the brakes, and in no case should more than two applications 
be necessary. A 5- or 6-pound reduction should be made at 
the proper distance from the stopping point, and this should be 
followed by a sufficient number of 2- or 3-pound reductions to 
bring the train to rest gradually at the proper point. The 
brakes should be released just before the train stops, so that 
the car trucks can right themselves while it is still in motion. 
If this precaution is not taken, there will be an unpleasant 
lurch backwards just as the train stops. 

Stops on Grades. — In making a stop on a grade where the 
brakes must be held on, it is best to use two applications of 
the brakes. The first application should be made as though 
the train were to be stopped a little short of the actual stopping 
point; then release the brakes (without recharging at all) when 
two to four car lengths from the stopping point, according to con- 
ditions. As soon as the car trucks right themselves, apply the 
brakes again lightly and leave them on. A light application, 
such as would be made in a case of this kind, does not tilt the 
trucks much; consequently, no surge is felt as the train stops. 
On some roads, all service stops with passenger trains are made 
with two applications of the brakes, and such practice gives 
good results. 

Overcharging Train Pipe. — In releasing the first application 
preparatory to making the second, when stopping a train, the 
brake valve should be thrown to full release and then immedi- 
ately moved to lap position, as otherwise the train pipe will be 
overcharged. The aim should be to just raise the train-pipe 



§3 THE AIR BRAKE. 21 

pressure sufficiently to release the brakes without trying to 
recharge the auxiliaries any. The feed groove in the triples is 
small, and if the brake valve is left in release position so long 
that the train pipe is charged 15 or 20 pounds higher than the 
auxiliaries, these latter may not have time to equalize with the 
train pipe before the second application has to be made. Sup- 
pose that the train-pipe pressure is 6 or 7 pounds higher than 
the auxiliary pressure when the second application is about to 
be made: to set the brake with the first reduction, the engineer 
must make a 12- or 13-pound reduction — 6 or 7 pounds to 
make the train pipe equal to the auxiliary pressure, and a 
further reduction of 5 or 6 pounds to apply the brakes. If the 
engineer makes the ordinary reduction, the brake will not apply, 
and the train will either run past the stopping point, or else 
the engineer will have to make an emergency application, which 
will, when the train is running slowly, cause a very disagree- 
able lurch. The easiest way to avoid this is not to overcharge 
the train pipe when releasing the brakes. 

Number of Applications. — It is not good practice to make more 
than two applications of the brake in stopping a train. Every 
time the brakes are applied and released, the amount of air 
taken into the brake cylinder from the auxiliary is discharged 
into the atmosphere. This reduces the auxiliary pressure, so 
that on the second application it equalizes with the brake 
cylinder at a much lower pressure than on the first, while on 
the third application it equalizes at a very greatly reduced 
pressure. For example, if a brake is adjusted so that it will 
equalize with the auxiliary at about 50 pounds on the first 
reduction, it will equalize at about 30 pounds on the second, 
20 pounds on the third, and at only about 10 or 12 pounds on 
the fourth application. It will thus be seen that the power 
of the brake falls away very rapidly with each reduction; hence, 
the advisability of making but two reductions at the most. 

As already stated, two applications are advisable wrier 
making a stop on a grade. It will be found advisable, also, to 
make two applications whenever a close accurate stop is to be 
made, such as at water tanks or coal chutes. In each instance 



22 THE AIR BRAKE. §3 



the stop should be made according to the instructions just given 
for a stop on a grade, and the brakes should be held on until 
the water or coal has been taken. 

Holding Brakes On. — When the brakes are to be held on for 
any length of time, and the engineer's valve is of the D-8 type, 
it will be necessary to stop the pump when main-reservoir 
pressure is obtained; otherwise, it would continue to work and 
overcharge the main reservoir. This in turn would overcharge 
the train pipe as soon as the brake valve was placed in release 
or running position, skidded wheels would probably result, and 
any old or weak hose would be very likely to burst. 

Stopping by Means of Tail Hose. — When the train is to be 
backed some distance and stopped by one of the train hands 
by means of the tail liose, the engineer should carry his brake 
valve in running position until he is given a signal or feels the 
first application, when he should immediately place the brake 
valve on lap. During the run backwards the brake valve must, 
of course, be carried in running position to supply any train- 
line leaks, but it should be lapped in time so that the man 
making the stop will not be hampered and will have complete 
control of the train, since he is the man that is responsible for 
the way the stop is made. 

29. Part- Air Freight Trains. — The amount of free 
slack in a part- air train is principally what makes such a train 
so difficult to handle without producing shocks, and, every time 
the speed of the train is altered, this slack must be taken care of. 
As already remarked, this free slack must either be gathered in 
or run out every time the speed of the train is changed, and 
the more quickly this is accomplished, the greater will be the 
resulting shock. Also, as remarked in Art. 3, the extent of the 
shock will depend on the number and position of the loaded cars 
in the non-air section, and on the extent to which the air section 
resists the blow as the slack is bunched or run out. If there is 
a sufficient number of air cars to hold well and the loads are at 
the rear end of the train, the shock will be severe if the slack 
is bunched quickly; consequently, a train should always be 
bunched or stretched gradually. 



§3 THE AIR BRAKE. 23 

In making a service stop with a part-air train, close the 
throttle at a sufficient distance from the stopping point, and let 
the train drift for a short distance, or until it has bunched 
fairly well. A reduction just sufficient to close the leakage 
grooves should then be made, and ample time allowed for any 
slack to run in before a second reduction is made. The second 
and succeeding reductions should be sufficiently light and 
numerous to bring the train smoothly and gradually to rest at 
the proper point, care being taken that one reduction is not 
made until after the train-pipe exhaust of the previous one 
has ceased. 

As a rule, the brakes should be held on until the train has 
come to rest, as otherwise a shock tending to tear the train in 
two will be caused, due to the slack running out. They should 
be released immediately after stopping, however, so that the 
brakes on the air cars may not be rigidly set when the non-air 
cars run back — as they will do when the spring slack eases up. 

Use of Hand-Brakes. — It should not be necessary to use hand- 
brakes to assist the air brakes in making a service, stop, but in 
case this has to be done, the brakes immediately back of the air 
cars should be used, and not those at the rear end of the train. 
AVhen hand-brakes are used, they should be released before the 
air brakes, as otherwise a break-in-two is liable to occur. In 
backing a part- air train out of a siding, however, a few hand- 
brakes should be applied at the rear end of the train before the 
air brakes are applied, so that the slack of the non-air section 
will not run out violently when the air brakes are applied to 
stop the train. • 

Water- Tank and Coal-Chute Stops. — It is a very difficult 
matter to apply or release the brakes of either a part-air or an 
all-air freight train at slow speeds, without a more or less severe 
shock resulting; hence, the safest way to make a close, accurate 
stop with a freight train is to stop short of the tank or chute, 
cut the engine off, take coal or water, and then couple up to 
the train again. 

A good way to make an accurate stop with a "lone" 
engine is to apply the brake in such a way that it will 
tend to stop 3 or 4 feet short; then, without releasing, use 



24 THE AIR BRAKE. §3 



a little steam just before it ceases to move, and the instant 
the throttle is closed the engine will stop. 

30. All-Air Freight Trains. — Although in making 
stops with an all-air train the engineer does not have to deal 
with a lot of free slack, as in the case of a part-air train, yet if 
the train is very long, he will have trouble with slack, since the 
head-end brakes apply and release sooner than the rear ones, 
in consequence of which, the slack plays in or out when the 
first reduction is made or the brakes are released. Also, as 
stated in Arts. 4 and 5, uneven distribution of load and 
unequal travel of the brake pistons complicate matters so that 
good judgment and skill must be exercised in handling such 
a train or else rough treatment of freight is sure to follow. 
Both the first and succeeding reductions must be heavier 
(according to the length of the train) than for short freight or 
for passenger trains (see Arts. 28 and 29). The first should 
be sufficient to cover all of the leakage grooves, and no succeed- 
ing reduction should be made before the train- pipe exhaust, due 
to the previous one, has ceased. After one or two applications 
of the brake, the engineer can judge pretty closely what reduc- 
tions to make in order to handle the train smoothly. 

In making a service stop with a long all-air freight train, 
the first reduction should be made at a sufficient distance 
from the stopping point, and once the brakes are applied they 
should be held on until the train has come to a standstill. It is 
almost impossible to release the brakes on a very long train 
at slow speed* without breaking the train in two, unless the 
retainers are used on the engine. Some roads are equipping 
their engines with retainers or other appliances that are intended 
to prevent the slack from running out violently in case it is 
necessary to release at slow speeds. 

If necessary to release brakes while the train is moving, 
sufficient excess pressure should be pumped up to insure the 
prompt release of the brakes, and the engine retainers, if the 
engine is supplied with them, should be cut into service. Care 
should always be taken not to work steam until all brakes on 
the train have released, and even then the throttle should be 



§3 THE AIR BRAKE. 25 

opened cautiously; for, if steam is worked before the rear-end 
brakes have released, the train is tolerably certain to be torn in 
two. After releasing the brakes, one second for each car in the 
train should be allowed before steam is used, so that sufficient 
time will be allowed for all brakes to release and the drawbar 
springs to adjust themselves. 



EMERGENCY STOPS. 



31. Brake Stops. — In cases of actual emergency, the 
brake valve should be thrown to full emergency position and 
left there, and sand should be used. Of course, it is possible 
to get the emergency action of the brakes without losing all the 
train- pipe air, but it is not good policy to try to do so in times 
of pressing danger. In the first place, if several cars with plain 
triples or with brakes cut out happen to be placed together, 
only the brakes ahead of such cars will go into quick action, 
while the ones back of them will set with a partial-service 
application only. If the valve is left in emergency position, a 
full application will be had on the cars back of, and full emer- 
gency on those ahead of, the cars with plain triples. Another 
possibility is that during the excitement the engineer may, in 
trying to bring the valve back to lap, move it to running 
position, thus releasing the brakes; or, if the valve is moved to 
lap too quickly, the surge of the air in the train pipe may 
kick off the forward brakes. 

Everything considered, the safest plan is to move the brake 
valve to emergency position and leave it there, and not try to 
save air in the hope that if the train can be stopped in time the 
brakes can be released and the train backed up and thus avoid 
the danger. No matter what the position of the brake valve 
or the kind of train — whether all-air or part-air — in case of 
emergency, the brake valve should be moved to emergency 
position. It makes no difference whether the brakes have been 
applied in a partial, or even a full, service application — the 
handle should be moved to emergency just the same. In the 
former case, a full-emergency application may not be obtained, 
but a partial emergency may; and certainly a full-service 



26 THE AIR BRAKE. 



application would be. In the latter case, if all the brakes were 
set full, no advantage would be gained, but if any of the brakes 
had not equalized with their auxiliary, or if some of the 
brakes had partially or wholly leaked off, the reduction 
would cause them to equalize with their auxiliaries, thus 
making them hold better. 

32. Reversing the Engine. — No matter how poor the 
driver- and tender-brakes are, if they are applied, the engine 
should never be reversed with the expectation of making a 
shorter stop than could be made with the brakes alone; revers- 
ing the engine under such conditions may cause the brake to 
lock and slide the drivers, in which case the retarding power of 
the engine is practically lost. It was proved by actual trial in 
the Galton-Westinghouse tests in England, and, later, in tests 
made by Mr. Thomas, Jr., Assistant General Manager of the 
N. C. & St. L. R. R. , that a stop cannot be made in as short a 
distance with the driver brakes set and the engine reversed as 
when the brakes alone are used. 

33. Accidental Emergency Stops. — Under this head 
are supposed to be included all emergency stops other than 
those purposely made by the engineer. Whenever the brakes 
apply suddenly without his aid, he should immediately lap the 
brake valve and leave it in that position, so as to bring the train 
to a standstill as soon as possible and save main- reservoir pres- 
sure for releasing brakes when the proper time comes for so 
doing. A sudden, unexpected application of the brakes may be 
caused by a conductor's valve being opened, by a burst hose, 
or by the train parting. 

RUNNING. 



POSITION OF BRAKE VALVE. 



34. The brake valve should always be carried in running 
position while the brakes are off, since this is the only position 
in which excess pressure can be carried, and train-pipe leaks 
supplied by air from the main reservoir. In speaking of 



§3 THE AIR BRAKE. 27 



excess pressure, it is meant that there is an excess of pressure in 
the main reservoir over that in the train pipe; that is, when 
main-reservoir pressure exceeds train-pipe pressure by a certain 
amount, that amount is called the excess pressure. The excess 
pressure, therefore, is carried in the main reservoir, and it is 
very important that it be carried and maintained at all times 
while the train is running. A sufficient excess should be carried 
so that when it is turned into the train pipe to release the 
brakes, it will do so promptly and also recharge the auxiliaries 
promptly. 

The brake valve should not habitually be carried in release 
position; in fact, ordinarily, it should not be carried there at 
all. It should simply be moved to, and left in, that position 
until brakes have been released, when it should at once be 
moved to running position. 

If an F-6 brake valve is left in release position too long, the 
train pipe will equalize with the main reservoir at 90 pounds 
pressure. If the valve is then moved to running position, the 
feed- valve will be held closed until train-pipe pressure has been 
reduced 20 pounds, or from 90 to 70 pounds. In case the train 
pipe has been overcharged, it is best to make a number of light 
applications and releases to reduce the train-pipe pressure to 
70 pounds. 

If a D-8 valve is left in lap position until the main reservoir 
is overcharged, the train pipe will be overcharged as soon as the 
valve is moved to running position, but the regular amount of 
excess pressure will still be carried. If the train pipe is so badly 
overcharged that it is advisable to reduce it, apply lightly and 
release a few times, as before. 



SETTING OUT A CAR. 

35. In setting out a car at a way station, first of all release 
the brakes; then close the angle cock on each side of the hose 
that is to be parted; then part the hose by hand, and hang up 
properly in the dummy couplings the hose of the car that is 
to be set out. Before the car is left in the side track, the air 
brake should first be released and then the hand- brake applied 



28 THE AIR BRAKE. §3 

(if necessary) to hold the car. The air brake should never be 
depended on to hold one or more cars on a grade for any length 
of time when not connected to the engine, since the brake may 
leak off and allow the cars to escape down the grade uncon- 
trolled. In case cars must be left standing on a grade, always 
release the air brakes and apply the hand-brakes. 



PICKING UP CARS. 

36. When the engine is backed up to a number of cars that 
are to be switched or picked up, the train pipe and auxiliaries 
on which cars may be empty, it is well to apply and release the 
engine brakes a couple of times without recharging the aux- 
iliary, and then place the brake valve on lap before the tender 
angle cock is opened. The auxiliary pressures on engine and 
tender will then be so low that if the engine brake does set in 
full when the angle cock is opened, the auxiliary and brake 
cylinders will equalize at such a low pressure that the main- 
reservoir pressure can very readily release them, and thus time 
will be saved, as the cars can be charged while they are being 
moved. 

In coupling up a car or cars that have been picked up, and 
which may not be fully charged, the following precautions 
should be observed: First, be sure that the rear angle cock on 
the rear car is closed; then, after coupling the hose, open the 
angle cock on the car that was picked up, and then the one on 
the charged section of the train, opening the latter cock slowly 
so that pressure will not be fed into the undercharged car faster 
than it is supplied to the train pipe from the main reservoir. 
By taking this precaution, both time and air will be saved. 



HOSE BURSTING. 

37. As already mentioned, in the event of a hose burst- 
ing, the engineer should immediately lap the brake valve, and, 
as soon as the train stops, send out flags. The hose should be 
replaced by a new one (if at hand) or by the extra hose on the 
last car of the train, and the brakes then tested to see whether 



§3 THE AIR BRAKE. 29 

they operate properly. If unsafe to replace the hose and test 
the train at the time, the angle cock immediately in front of the 
burst hose should be closed; the brakes back of it should then 
be bled off, and the train moved to a safe place, where the hose 
can be replaced and the brakes tested. 

To Locate a Burst Hose. — If the leak is not too large, the 
brake valve should be left in partial-running position; the leak 
can then be located by the sound made by the escaping air, 
while at the same time main-reservoir pressure can be main- 
tained. With a large leak, however, it would be impossible to 
open the valve wide enough to make a sound and still main- 
tain the main-reservoir pressure; consequently, the brake valve 
should be moved periodically from lap to full release and back 
again. This will produce an intermittent sound by means of 
which the leak can be located. 



BLEEDING BRAKES OFF. 

38. There are two methods by which a triple valve can be 
made to release a brake. One is to increase the train-pipe 
pressure above that in the auxiliary — the other to reduce the 
auxiliary pressure below that in the train pipe. The first is 
the usual way — the second method is the one employed to 
bleed off a brake. To do this, the release valve, or bleed cock 
as it is often called, should be held open until air escapes from 
the triple exhaust, when it should immediately be closed. The 
blow at the exhaust indicates that the triple has moved to 
release position, and any further reduction of auxiliary pres- 
sure is not only a loss of air, but also causes a reduction in 
the train-pipe pressure, which in some cases may cause other 
brakes to apply. 

BREAKING-IN-TWO OF TRAIN. 

39. In case an all-air train should break in two, the brake 
valve should be lapped at once and the engine throttle closed, 
so as to bring the front section to a standstill as soon as 
possible. With such a train, the engineer should not attempt to 
keep the head end out of the way of the rear end, for the reason 



30 THE AIR BRAKE. 



that they are pretty sure to come together in any event; and 
the less the two sections separate, the less damage will be done 
when they come together. Flags should be whistled out, and 
as soon as the sections come to a standstill, the last angle cock 
of the front section should be closed and the brakes on that sec- 
tion released. As soon as the signal is given, the front section 
should be backed up and coupled to the rear section, and the 
brakes on the whole train released. A test should then be 
made to see whether the brakes are working properly. 

In the event of a part-air train breaking in two, the course to 
pursue will depend on whether the break occurs in the air 
section, or back of it. If it occurs in the air section, pursue the 
same course as with an all-air train; if it occurs in the non- 
air section, the brakes, of course, will not set on the air section, 
and the engineer should endeavor to keep the head section out 
of the way of the rear section until the latter can be brought 
to a standstill. 

HANDLING TRAINS ON LONG DOWN GRADES. 

40. The manner in which the braking should be done on a 
long down grade depends, to a considerable extent, on local 
conditions, which may differ widely on different hills; conse- 
quently, no rule can be given that will cover all conditions. In 
order to give instructions for braking on any particular hill, the 
location of the easy and heavy parts of the grade should be 
definitely known; hence, instructions are usually issued by the 
companies, covering the conditions in each case. 

In the absence of specific instructions, however, the following 
will serve as a guide: The pump should be run faster than 
usual while on the grade, so as to recharge the main reservoir 
promptly when necessary. Turn the retainer handles up just 
before the descent is begun, and make a moderately heavy 
reduction while the speed of the train is slow. It will be 
remembered that a given reduction will cause the brakes to 
hold better at slow, than at high, speed; hence, much better 
control of the train can be maintained, and air saved, by 
making the first reduction before the train has gained much 
headway. Good judgment should be used in making the 



§3 THE AIR BRAKE. 31 



succeeding reductions, and they should be sufficient in num- 
ber and amount to maintain the speed of the train well within 
safe limits. 

When possible, curves and easy parts of the grade should 
be selected on which to release the brakes and recharge the 
auxiliaries; also, the last reduction before releasing should be 
heavier than the others, so as to slow down the speed consider- 
ably before releasing, since it not only will take a little longer 
for the brake-cylinder pressure to reduce down to 15 pounds, 
but the pressure in the brake cylinder will have a greater retard- 
ing effect at the slower speed. The auxiliaries should be fully 
charged just before the steep parts of the grade are reached, so 
as to have sufficient braking power to hold the speed within 
bounds while descending. Safety should, of course, be the first 
consideration, and, in general, the best results will be obtained 
by a slow speed and the use of retainers while on the grade. 



QUICK ACTION DURING SERVICE REDUCTION. 

41. If, when making a service reduction, the brakes set 
quick action, the trouble may be: (1) a broken pin in the 
graduating valve of the triple; (2) the graduating valve badly 
gummed up; (3) the triple piston gummed up or frozen, so 
that it will not respond to an ordinary train- pipe reduction; or, 
(4) if the train is short, a broken graduating spring 22 in the 
triple. In sections 3 to 6 of Art. 28, Part 2, it was explained 
how these defects cause the brake to apply quick action. 



LOCATING DEFECTIVE TRIPEE. 

42. Quick action during a service reduction is due to one 
of the triples, for some reason, not operating in service posi- 
tion, but only in emergency position, thus causing the others to 
fly on also. If the trouble is due to a sticky triple, or to a 
broken or gummed-up graduating valve, it may be located as 
follows: Make a light service reduction and, since all brakes 
but the defective one will apply, look for a brake that has not 
set. This, when found, may be cut out at once and the brakes 
again tested, to see if the brake cut out is the one that has been 



32 THE AIR BRAKE. §3 

causing the trouble. Another method is to make a light reduc- 
tion and, when a brake is found that has not applied, make a 
second or even a third reduction, if necessary, while some one 
watches the brake to see if it goes on quick action only; if so, it 
should be cut out. Should the trouble be due to a weak or 
broken graduating spring 22, the triple will move to emergency 
position when a light reduction is made, and thus cause all of 
the brakes to fly on. Generally, a triple with a broken gradu- 
ating spring is rather hard to locate. To do so, the brakes may 
be watched to see which goes on quick action first; or an angle 
cock in the middle of the train may be closed to see on which 
half the defective triple is located, this being repeated with the 
portion of the train containing the defective triple until but a 
few cars have to be watched. These can either be cut out one 
at a time, or else they can be watched to see which piston moves 
out first. When located, the defective triple should be cut out. 



BRAKES STUCK ON. 

43. If it is found that the brakes cannot be released by 
placing the brake valve in full-release position, it should be 
placed on lap to obtain excess pressure, and then thrown into 
full release. The brakes on a long train with quick-action 
triples are especially liable to stick after an emergency applica- 
tion, on account of the auxiliary and brake cylinder equalizing 
at a higher pressure than usual. On a very long train the rear 
brakes are liable to stick after a very light application, because 
the train- pipe pressure cannot be raised enough to move the 
sticky triple; with a heavier reduction this triple will very 
likely release promptly. 

USE OE SAND. 

44. It is well known that by the proper use of sand the 
wheels may be made to grip the rails much better, thus 
lessening the danger of the wheels being flattened from sliding. 
On the other hand, if the sand is not properly used and the 
wheels begin to slide, the flat spots formed will be worse than if 
no sand were used. 



§3 THE AIR BRAKE. 33 

When necessary to use sand in making a stop, the rails under 
the entire train should be sanded by the time the first applica- 
tion is made, or at least before the brakes have applied very 
hard, and the sand should be used continuously until the train 
comes to a standstill. Sand should never be used after the 
wheels have begun to slide, since it will not start them turning 
again, but will simply increase the wear on the wheel and thus 
make the resulting flat spot larger than it otherwise would be. 
In the event of the wheels sliding, the brakes should be 
released, if practicable, and the rails sanded; after which the 
brakes may be applied again, but the rails should be con- 
tinuously sanded until the stop is made. Whenever the rails 
are bad, sand should be used in applying the brakes, to avoid 
skidding the wheels. It is bad practice to attempt making a 
stop without using sand and then, after the brakes have been 
fully applied and it looks as though the train would not stop 
soon enough, to drop sand on the rails. Some of the wheels 
may be sliding at the time, and the sand will thus be the cause 
of some very bad spots. 

WHEELS SLIDING. 

45. When the brakes are applied, there are two forces 
acting on the wheels: one, the force exerted by the brake, 
which tends to prevent the wheel from turning, and thus tends 
to cause it to slide over the rail like a sled runner; the other, 
the force exerted between the wheel and the rail, which resists 
this tendency to slide, and thus tends to keep the wheel turning. 
As long as the latter force is greater than the former, the wheel 
will continue to revolve; but if, for any reason, the force exerted 
by the brake is the greater, the wheel will slide. It will thus 
be seen that a wheel may be made to slide either by reducing 
the adhesion between the wheel and the rail (as when the rails 
are greasy), or by increasing the force exerted by the brake 
above a certain amount. 

Apart from the matter of slippery rails, therefore, the wheels 
may be slid: if the piston travel is too short, whether due to its 
adjustment, to the hand-brake being partially set, or otherwise; 
if the leverage is too great; if the brake fails to release after 



34 THE AIR BRAKE. 



a heavy application in making a stop; if a heavy reduction 
is made when the train is moving slowly; or if the auxiliaries 
are overcharged and allowed to equalize with the brake 
cylinders. Some types of driver brakes may lock and skid the 
wheels if the piston travel is allowed to become too long. 

USE OF CONDUCTOR'S VALVE. 

46. In passenger service, each car is provided with a valve 
called the conductor's valve (see Fig. 1, Part 1), by means of 
which the brakes can be applied from the cars. This valve is 
connected to the train pipe by means of a branch pipe, and 
when the valve is open it makes a direct passage from the train 
pipe to the atmosphere. The conductor's valve is intended to 
be used only in cases of emergency, when it is necessary to stop 
the train as soon as possible. It should be opened gradually 
and held open until the train comes to a stop, for if it should be 
closed while the engineer's brake valve is in running position, 
the brakes will be released again. 

DOUBLE-HEADING. 

47. In double-heading, it is the duty of the leading engi- 
neer to handle the brakes, and the cut-out cock in the train 
line under the brake valve of the "following" engine should 
be closed, so as to give him absolute control. After closing 
the cut-out cock, the engineer of the following engine should 
place his brake valve in running position and keep his pump 
operating so as to maintain the full main -reservoir pressure in 
case the leading engineer desires assistance in releasing brakes. 
In that event; the following engineer should open the cut-out 
cock under his brake valve and place his valve in full release, 
but the brake valve should be moved to running position, and 
the cut-out cock closed again as soon as the brakes release, or 
the control of the train will be taken away from the leading 
engineer. 

If the following engine is not supplied with a cut-out cock, 
the brake valve should be carried on lap instead of in running 
position; a blow may then occur at the train-pipe exhaust 
when brakes are released. When the leading engineer places 



§3 THE AIR BRAKE. 35 

his brake valve in release position, he increases the train- pipe 
pressure above that in chamber D of the following engineer's 
brake valve, and the equalizing piston of that valve may be 
raised, and open the train-pipe exhaust. In this event, the 
brake valve should be placed in full release until the blow 
ceases, and then be returned to lap. 



PISTOL TRAVEL AND ITS ADJUSTMENT. 



LONG AND SHORT TRAVEL. 

48. The subject of piston travel and its adjustment is 

an important one, and should be thoroughly understood, since 
not only the efficiency of the brake, but also the smoothness 
with which a train can be handled, depends to a great extent on 
the proper adjustment of the brake-piston travel. 

The auxiliary reservoir used with any brake cylinder is of 
such a size that if charged to 70 pounds it will equalize with the 
brake cylinder at 50 pounds, if the travel of the brake piston is 
adjusted to 8 inches. If the piston travel is less than 8 inches, 
the auxiliary and brake cylinder will equalize at a higher 
pressure than 50 pounds, while if the travel is more than 
8 inches, they will equalize at a lower pressure. When a train- 
pipe reduction is made, air passes from the auxiliary (into the 
brake cylinder) until the pressures in auxiliary and train pipe 
are about equal. Thus, for a given train-pipe reduction, the 
same amount of air is discharged into the brake cylinder, 
regardless of the length of the piston travel. That is to say, if 
a 7-pound reduction were made, the same amount of air would 
pass into a brake cylinder having a 5-inch piston travel as 
would pass if the travel were 8 inches. With the 5-inch travel, 
however, the air would have to occupy less space than with the 
8-inch travel; hence, it can readily be seen that the brake with 
the short travel will develop the greater pressure. 

EQUALIZATION TESTS. 

49. The following table gives the results of a number of 
tests made with a freight equipment, each pressure given 



36 



THE AIR BRAKE. 



being the average of several trials with each piston travel. 
It shows the pressure obtained in the brake cylinder for 
different piston travels in both service and emergency appli- 
cations of the brake. 

BRAKE-CYLINDEE PRESSURES. 



Service Reduction From 
70 Pounds Train Pipe. 


Piston Travel. 


4" 


5" 


6" 


7 // 


8" 


9" 


10" 


11" 


7 


25 


23 


17* 


13 


10* 


8 






10 


49 


43 


34 


29 


23 J 


19* 


17 


14 


13 


57 


56 


44 


37* 


33 


29 


24 


20 


16 






54 


47* 


41* 


35 


29 


24 


19 








51 


47 


40 


36* 


32 


22 










50 


47* 


44 


39 


25 














47 


45 


Emergency reduction 


62 


61 


59* 


m 


57* 


56* 


55* 


55 



Explanation of Table. — The first column on the left gives 
the reduction in train- pipe pressure; the second column gives the 
brake- cylinder pressure resulting from the corresponding reduc- 
tion in column 1, when the brake- piston travel is only 4 inches; 
the third column gives the resulting brake-cylinder pressure 
when the piston travel is 5 inches, and so on for the other 
columns. For example, a train-pipe reduction of 7 pounds will 
result in a brake- cylinder pressure of 25 pounds with a 4-inch 
travel, or 8 pounds with a 9-inch travel; a 10-pound reduction 
will result in 43 pounds brake-cylinder pressure with a 5-inch 
travel, and only 14 pounds with an 11-inch travel. 

By studying the table carefully, some very useful information 
may be derived. It will be found that short-travel brakes 
equalize quicker, and with a less reduction, and also exert a 
greater pressure than do long-travel brakes. For instance, a 
13-pound reduction will cause all brakes with 4-inch travel to 
equalize at 57 pounds pressure, and with 5-inch ones to equalize 
at 56 pounds; while a 25-pound reduction is necessary to set a 
brake full with a 10- or 11-inch travel, and then they equalize 
at only 47 pounds and 45 pounds, respectively. 



§3 THE AIR BRAKE. 37 

It will be seen, also, that if three brakes, with, say, 4-, 8-, and 
11-inch travel, respectively, were in the same train, the retard- 
ing force exerted by each would vary greatly at each -reduction. 
For instance, a 7-pound reduction would cause the first to 
develop 25 pounds pressure per square inch; the second, 10^ 
pounds; while the pressure in the cylinder having the 11-inch 
travel would not be sufficient to move the piston out the full 
stroke. Now, if the brake cylinders were of 10-inch diameter, 
a pressure of 25 pounds per square inch in the short- travel 
brake would develop a total force of 1,963 pounds; 10J 
pounds per square inch in the medium-travel brake would 
develop a total force of 825 pounds; while the long-travel brake 
would hardly develop sufficient power to force the piston to 
its full stroke. Thus, of these three brakes, with a 7-pound 
reduction, the holding power of the first would be nearly 
2J times as great as that of the second, while the third would 
be altogether ineffective. It is this difference in holding power, 
due to unequal piston travel, that makes it so difficult to 
handle freight trains smoothly. 

To sum up briefly, the table shows: (1) that the short- 
travel brakes in a train hold harder at each reduction than the 
long- travel ones; (2) that they equalize with their brake cylin- 
ders with a less train-pipe reduction, hence equalizing sooner 
than the long- travel brakes; (3) that they equalize at a higher 
pressure; (4) that since they equalize at higher pressure, they 
must release later than the brakes with long travel after a 
full reduction. 

When the train -pipe pressure is increased to release the 
brakes, it will release those having a 10-inch travel at 47 
pounds pressure, but it must be increased 9 pounds more, or to 
56 pounds, to release those having a 5-inch travel. As soon as 
the first brakes release, their auxiliaries commence recharging, 
thus making train-pipe pressure increase more slowly than it 
otherwise would, and delaying the release of the short-travel 
brakes. If sufficient excess pressure to release the short-travel 
brakes is not carried, the wheels will probably be slid while 
the brakes are being pumped off, and bad spots will result. 
Besides this, the train is subjected to severe wrenches tending 



38 THE AIR BRAKE. §3 



to break it in two, on account of the long-travel brakes 
releasing before the others. However, if the travel is adjusted 
within certain limits, all brakes will start releasing at about the 
same time, the tendency being for the long-travel brakes to 
release first. If the travel were uniform throughout the train, 
the tendency would be for the brakes nearest the engine to 
release first, since train-pipe pressure is increased there first. 
If none of the brakes have been set in full, they should begin 
releasing at about the same instant (regardless of the difference 
in piston travel); this is due to the fact that until a brake 
equalizes, its auxiliary pressure is practically equal to train- 
pipe pressure. 

The last row of figures in the table shows that the resulting 
brake-cylinder pressure obtained in an emergency application 
of the brakes decreases as the piston travel is increased. 



RUNNING TRAVEL. 

50. The piston travel is greater by from 1 to 2 inches 
when the train is running than when standing still, on account 
of (1) loose journal brasses, allowing the wheels to move; 
(2) loose boxes in pedestals; (3) loose truck kingbolts, allowing 
the trucks to pull together; and (4) the "spring" in the brake 
beams, levers, or connections. The amount that the brake 
piston travels when the brakes are applied and the train is in 
motion is called the running travel. Brake beams are some- 
times so hung that the brake shoes pull down lower on the 
wheels when the brakes are applied, and since in that case the 
shoes travel farther to touch the wheels, the piston travel is 
increased. 

Also, the travel is generally greater when the car is loaded 
than when unloaded. If the brake beams are hung to the side 
sills of a car or to the bolster, they will be lowered (conse- 
quently increasing the travel) when the car is loaded, and raised 
again (shortening the travel) when it is unloaded. To avoid 
this bad effect, some roads hang the brake beams to such a 
part of the truck that the center of the brake shoes is always 
the same distance from the rails, regardless of whether the car 
is loaded or not. The method gives very good results. 



THE AIR BRAKE. 39 



THE PROPER PISTON TRAVEL. 

51. The different parts of the air-brake apparatus are so 
designed and constructed that the proper brake- shoe pressure 
will be obtained — in a full-service application of the brakes — 
with a pressure of 50 pounds per square inch in the brake 
cylinder. The brake, therefore, would be safer and more 
efficient if the piston travel were always to remain such as to 
just give 50 pounds pressure in the brake cylinder — i. e. between 
7 and 8 inches — but as the brake shoes wear quite rapidly, the 
travel is bound to increase unless, as such wear proceeds, 
this travel is automatically adjusted by means of a slack 
adjuster. Automatic slack adjusters not being in general use, 
it has been customary on most roads to take up the shoe slack 
on passenger cars and tenders until the piston travel is about 
6 inches; the brake is then allowed to run until the wear of the 
brake shoe increases the travel to 8 inches, when the slack 
is again taken up. 

The limits between which the piston travel is allowed to vary 
are, on most roads, as follows: For passenger- car and tender 
brakes, between 6 and 8 inches; for standard freight cars, 
between 5 and 9 inches. On the engine, one auxiliary reservoir 
supplies a*ir for the two driver-brake cylinders; consequently, 
a 1-inch travel of each of the driver-brake pistons is equivalent 
to a 2-inch travel of a car-brake piston. On some roads the 
driver- brake piston travel is allowed to vary between J and § of 
the full stroke of the piston. The better practice, however, is to 
use an air gauge on the brake cylinder and adjust and maintain 
the travel so that 50 pounds per square inch will be obtained 
in the brake cylinder on a full application of the brakes. 

MEASURING THE PISTON TRAVEL. 

52. To measure the brake-piston travel, force the push 
rod — if one is used — into the sleeve until it bottoms on the 
brake piston, and the latter is forced against the cylinder head; 
then make a mark on the end of the cylinder and measure the 
distance between the mark and the center of the lever pin in 
the push rod. Apply the brake in full, and again measure 



40 THE AIR BRAKE. 



from the same mark on the cylinder to the center of the lever 
pin; the difference in the measurements will be the amount 
that the piston travels. 

If it is desired to measure the piston travel on an uncharged 
car, proceed as before, only in this case the brakes will have to 
be set by hand; if necessary, use a piece of wood or a bar of 
iron as a lever to set them up tight. This method can only be 
used on cars on which the air brakes and hand-brakes move the 
piston lever in the same direction in applying the brake. 



ADJUSTING BRAKES. 

53. Adjusting Car Brakes. — In regulating the piston 
travel of a car or tender brake {Hodge system), the slack of the 
brake shoes is taken up by means of the truck dead lever. 
This is accomplished by moving this lever so as to reduce the 
shoe clearance, since the smaller this clearance, the less the 
piston will have to move to draw the shoes up against the wheels. 
The top of the dead lever is held by a pin that runs through a 
guide and the lever, the top of the lever traveling between the 
sides of the guide. The position of the lever in the guide can be 
changed by removing the pin and moving the lever until it 
connects with one of the many holes in the guide. Extra holes 
are sometimes put in other connections of the brake rigging so 
that, if necessary, part of the slack may be taken up there. 
For instance, if sufficient slack cannot be taken up at the truck 
dead lever, one or two holes should be taken up in the other 
connection and the travel then adjusted by means of the truck 
dead lever. 

On most freight cars, both the hand-brake and the air brake 
move the levers in the same direction in applying brakes; 
hence they are said to work together. On nearly all passenger, 
and a few freight, cars, however, the hand-brake and the air 
brake move the levers in opposite directions; if, then, the hand- 
brake chain is wound up a little, the piston travel will shorten 
a corresponding amount when the air brake is next applied. 
When the hand-brake and the air brake work together, winding 
up the brake chain does not shorten the piston travel. 



THE AIR BRAKE. 



41 



□ 




42 THE AIR BRAKE. §3 



The practice of shortening the piston travel by winding the 
hand-brake up a little, instead of moving the dead lever, is a 
bad one, and is decidedly dangerous. If the brake dog on the 
hand-brake should work out of the ratchet, the slack would run 
out; also the extra strain on the brake chain tends to break it. 
If too much chain is wound up,. the travel may be shortened so 
much that the piston will not cover the leakage grooves and the 
brake will not apply. Then, again, if the air brake tends to 
turn the hand-brake wheel in a direction opposite to that which 
it must be turned by hand to set the brakes, there is always 
danger of a person being hurt should he try to turn the hand- 
brake when the engineer happens to be setting the air brakes. 

54. Cam Driver-Brakes. — In Fig. 1 are shown two 
views of the push-down type of cam driver-brake, (a) being 
a side view, and (6) an end view. As air is admitted into the 
brake cylinder C, the piston and, consequently, the crosshead 
h are forced downwards, thus causing the cams to roll on each 
other and move the cam-screw pins outwards, pressing the shoes 
against the. wheels. 

The distance between the link pin a and the cam-screw pin b 
can be changed by means of the cam-screw c, and it is by means 
of this screw that the piston travel is adjusted. To shorten the 
travel, the distance between the pins is lengthened. 

In taking up the slack of the brake shoes, care must be exer- 
cised to lengthen both cam-screws the same amount, so that the 
point of contact of the cams will be in line with the center of 
the brake cylinder. Sufficient shoe clearance should be allowed. 

55. Outside Equalized Driver Brake. — In Fig. 2 are 
given two views of the American outside equalized driver 
"brake as generally used at the present time on engines having 
three or more pairs of drivers, (a) being a side view and (5) a 
plan view. In this type of brake the piston is connected to the 
brake rod R by a bell-crank lever L that turns on the pin P, so 
that when the brake piston is forced outwards, the brake rod R 
is drawn backwards and applies the brake shoes to the wheels. 

A slack adjuster T (popularly spoken of as a turnbuckle) is 
provided for the purpose of taking up the slack as the brake 




S 6 



44 THE AIR BRAKE. §3 



shoes wear. This is accomplished by loosening the locknut s 
on the screw bolt, and turning the bolt in such a way as to pull 
the brake rod R backwards, thus moving the brake shoes up 
nearer to the wheels. The pipe p leads from the brake cylinder 
to the triple valve. 

BRAKE GEAR. 



SEVERS AJND TjETERAGE. 

56. The foundation brake gear on engines, tenders, and 
cars consists simply of a system of levers connected together by 
rods; and it is by means of these levers that the force developed 
in the brake cylinder is transmitted and applied to the wheels. 

It is desirable, therefore, to be able to calculate the braking 
power that a system of levers is capable of exerting, and to do 
this the different classes of levers must be studied. 

SIMPLE LEVEES. 

57. The Straight Xiever. — A lever is any bar that is 
capable of being turned about a fixed axis or pivot, called the 

fulcrum, as in Figs. 3, 
4, and 5. In these figures, 
Wj the object to be lifted, 
is called the weight; the 
force P, employed to lift 
the weight, is called the 
power; and the point F, 
round which the lever 
turns, is called the ful- 
crum. That part of the 
lever Fb between the f ul- 
w \ crum and the weight is 

called the weight arm of 

the lever, while the part Fc between the fulcrum and the 

power is called the power arm. 

The fulcrum F, it is to be remembered, is stationary, and the 

lever is perfectly free to turn on it. Now, if the weight W is 



Fig. 3. 



§3 THE AIR BRAKE. 45 

great enough, it will cause the lever to turn or rotate about 
the point F against the action of the power P; if, on the 
other hand, the power \j>, 

is great enough, it will W 

cause the lever to rotate V > „ 

about F against the &p — 

action of the weight W. \l 

In other words, it will 

raise the weight. When FlG - 5 - 

the power P is just sufficient to balance the weight W, and 

the lever, therefore, does not move, it will be found that: 

Rule J..— The power multiplied by the power arm is equal to 
the weight multiplied by the weight arm. 

Thus, in Fig. 5, the power P, multiplied by the distance Fc, 
will just equal the weight W multiplied by the distance Fb. 

Or, expressing this in symbolic form, 

PXFc = WxFb. 

From this it can readily be shown, that 

p = *#; CD 

Fc = **!*; (3) 

where P stands for the force or power applied, W for the weight, 
Fc for the length of the power arm, and Fb for the length 
of the weight arm. 

It will be seen that only four quantities enter into these 
equations, as the above expressions are called, and if any three 
of these quantities are known, the other can be determined by 
means of one of the equations. The use of the equations, or 
formulas, is illustrated in the following examples: 

Example 1. — If the power arm of the lever is 20 inches long and the 
weight arm 10 inches long, what power must be applied to just balance 
a weight of 1,000 pounds? 



46 THE AIR BRAKE. 



Solution.— In this example we see that Fc = 20, Fb = 10, W= 1,000, 

and P is to be found; therefore, substituting these values in formula (1 ), 

we find that 

p WXFb 1,000 X 10 , nn -. A 

P = =— — = ^ = 500 pounds. Ans. 

Fc 20 ^ 

Example 2. — If a power of 1,000 pounds is applied to the lever of 
example 1, how man}^ pounds weight will it balance? 

Solution.— In this example, Fc = 20, Fb = 10, and P = 1,000; 
Wis to be determined, hence equation (2) will be used. From this, 

w = W; = W0X 20 = 2000 pmmds Ang 

Example 3. — Suppose a force of 1,600 pounds at P has either to sup- 
port a weight or exert a force of 3,200 pounds at W. How long must the 
power arm be, the weight arm being 10 inches? 

Solution.— In this case, P = 1,600, W = 3,200, and Fb = 10. 

Therefore, 

WXFb 3,200X10 - . , 

Fc = ~-~ = , arv\ ~~ = 20 inches. Ans. 

r 1 , oOO 

Example 4. — If, in example 3, the power arm were 10 inches long, 
what length would the weight arm have to be ? 

Solution.— Here P = 1,600, W = 3,200, and Fc = 10; hence, 

PXPc 1,600X10 r . , . 

Fb = — ttf— = o -J^ — = 5 inches. Ans. 
11 3,200 

58. Suppose that the weight arm Fb of the lever shown in 
Fig. 6 is twice as long as the power arm Fc, then, if the lever 
is turned about the fulcrum F until it occupies any other posi- 

x , tion, as b' Fc', it will be 

^\ found by actual measure- 



w 



ment that the point b of 
the lever travels just 
twice as far in moving 
to b' as c does in moving 
to c' . If the weight arm 
were four times as long 
as the power arm, it 
would be found that the 
point b would always 
travel four times as far as the point c when the lever was 
moved through any distance. In other words, the distances 



Fig. 6. 



THE AIR BRAKE. 47 



through which the power and the weight move are always in 
the game ratio as the lengths of their arms. 

This being true, we may, in place of the statement that the 
power multiplied by the power arm is equal to the weight mul- 
tiplied by the weight arm (rule I), write: 

Rule II. — The power multiplied by the distance through which 
the power moves is equal to the weight multiplied by the distance 
through which the weight moves. 

If the power moves through a distance c c'. while the weight 
moves through a distance b b f , then by substituting c c' and b b' 
for Fc and Fb, respectively, in the equations (1) and (2) of 
Art. 57, we have: 

WX bb' . TJ/ PX cc' 
and W 



cc' ' bb' ' 

Example 1. — If the point of application b of the weight travels 
2 inches while the point of application c of the power travels 8 inches, 
what force must be exerted on the lever to cause it to exert a force of 
2,000 pounds? 

Solution. — In this case, cc' = 8, hi' == 2, and W = 2,000; hence, 

p WXbV 2,000 X- 2 , m , . 

P = -. — = — — - = 500 pounds. Ans. 

cc' 8 

Example 2. — In the above example, if a force of 1,000 pounds is 
applied at P, what force would the lever exert at W? 

Solution. — Here, again, the weight moves 2 inches while the power 
moves 8 inches; hence, 

w = £X£ = ^oooxs = 4;000 pounds Ans _ 

The principle embodied in rule II was made use of by 
Mr. H, A. Wahlert in inventing a method for determining the 
braking power developed by a cam driver-brake. 

59. Classes of Levers. — Levers are divided into three 
classes, depending on the relative positions of the fulcrum and 
the points of application of the power and the weight. 

In levers of the first class, Fig. 3, the fulcrum F is between 
the points of application of the power P and weight W. Fig. 7 
represents a car truck lever of this class applied to a car wheel. 



48 



THE AIR BRAKE. 



§3 



In levers of the second class, Fig. 4, the weight W is between 
the fulcrum F and power P. This class is represented in 
Fig. 8, as applied to a car wheel. 

In levers of the third class, Fig. 5, the power P is between 
the fulcrum F and the weight W. This class is represented in 

Fig. 9, as applied to a 
car wheel. 

60. The Weight 
Sustained hy the 
Fulcrum. — The force 
exerted on the fulcrum 
of a lever can be calcu- 
lated by assuming that 
the fulcrum has changed 
places with either the 
power P or the weight W, 
and then using the proper 

equation.. For instance, in example 1, Art. 57, it was found 

that a force of 500 pounds at P would balance 1,000 pounds 

at W, the lever arms being 20 

inches and 10 inches, respect- 
ively. Now, to find the 

force sustained at F, assume 

the fulcrum to have changed 

places with W. The power 

arm in that case would be 

20 + 10 = 30 inches long, 

while the weight arm would 

remain the same as before, or 

10 inches, and we should have 

PXFc 500 X 30 




Fig. 7. 




Fig. 8. 



w 



Fb 



10 



1,500 pounds. 



This, it will be noticed, is equal to the sum of the power P 
and weight W. 

If this method is applied to the three classes of levers, it will 
be found that: (1) the pressure on the fulcrum of a lever of 
the first class is equal to the sum of the power and weight; 



§3 



THE AIR BRAKE. 



49 



(2) the pressure on the fulcrum of a lever of the second class 

is equal to the difference between the weight and the power; 

while (3) the pressure on 

the fulcrum of a lever of 

the third class is equal 

to the difference between 

the power and the weight. 




Fig. 9. 



61. Bent Levers. 
All rules and equations that 
apply to the straight lever 
apply equally well to the 
bent lever, if care is taken 
to determine the true or 
virtual lengths of the lever 
arms. In the case of a straight lever with the forces acting at 
right angles to it, the arms may be measured along the lever 

c itself; in all other 

S \ cases (such as when: 

^' \ 1, the forces are par- 

allel, but act at an 
angle to the lever; 2, 
the forces do not act 
parallel to each other; 
or 3, if the lever is 
bent), the weight arm 
or power arm must be 
taken as the perpen- 
dicular distance from 
the fulcrum Fto the line 
of direction in which the 
weight or power acts. 

Figs. 11, 1.2, and 
13 represent different 
styles of bent levers. 
FlG - "■ L — ' In each case the power 

arm is represented by the line Fc, the weight arm being repre- 
sented by the line Fb. Fig. 10 is dealt with in the same way. 




50 



THE AIR BRAKE. 



§3 



COMPOUND LEVERS. 

62. Description. — A compound lever is a combination 
of simple levers so arranged that when a power is applied to 
the first lever it actuates all of the others and causes a force to 
be exerted by the last lever of the combination. When a force 




Fig. 12. 

is applied to the first lever, it exerts a force that is applied to 
the second lever; the force exerted by the second lever is 
applied to the third; and so on. 

Such a lever is shown in Fig. 14, in which there are three 
simple levers; the weight arm of the first is connected to the 
power arm of the second, and the weight arm of the second to 
the power arm of the third. It will be seen that by applying 
sufficient power at P to operate the first lever, the others will 




Fig. 13. 

also be operated, and the weight W oi the third lever will be 
raised. 

It will be noticed, also, that the force exerted by the end of 
the weight arm of the first lever is the power applied to the 
second; and the force exerted by the second is the power applied 
to the third; and so on for any number of levers. 



THE AIR BRAKE. 



51 



63. Law of the Compound Lever. — The law that 
governs the compound lever may be stated as follows: The 
power P multiplied by the product of the power arms of all the com- 
ponent simple levers, is equal to the weight W multiplied by the 
product of the iveight arms of all these levers. 




Fig. H. 



From this law the following rules may be deduced: 

Rule III. — The power P that must be applied to a compound 
lever to balance a given iveight or produce a given pressure W, may 
be found by multiplying the product of the weight arms of all the 
simple levers by the weight, and dividing this by the product of the 
power arms of all these levers. 

Example.— How much power must be applied at P, Fig. 14, to balance 
1,000 pounds at W ? 

Solution. — The weight arms of the levers are 6, 6, and 18 inches, and 
the power arms 24, 18, and 30 inches, respectively. Hence, from rule 
III, the power 

6X6X18X1,000 __ - , . 
P = 24X18X30 = 5 °P° unds - Ans - 

Rule IV. — The iveight that a given power will balance, when 
applied to a compound lever, may be found by multiplying the 
product of the power arms of all the simple levers by the power, and 
dividing this by the product of the weight arms of all the levers. 

Example. — If a force of 50 pounds is applied at P, Fig. 14, how many 
pounds will it balance at W? 

Solution. — From rule IV it will be found that 50 pounds at P will 
balance a w r eight of 

24 X 18 X 30 X 50 



Il- 



ex 6X18 



1,000 pounds. Ans. 



52 THE AIR BRAKE. §3 



LAWS OF LEVERS APPLIED TO BRAKE GEARS. 

64. In order to apply these laws to any particular system 
of levers, it is best to make a diagram showing the position of the 
f ulcrums, the length of the lever arms, and the line of direction of 
the forces applied to, or exerted by, the levers. Then, since the 
force developed by the brake cylinder is generally known, the 
power exerted by the lever can be readily found by applying 
the proper rules or formulas. 

To illustrate the application of the laws of levers to actual 
brake gears, the braking power of the Hodge and the Stevens 
systems of car-brake levers, and of the cam and the American 
equalized types of driver brakes will be determined. 

65. The Hodge System. — A diagram of the Hodge 
system is shown in Fig. 15. It will be seen to consist of two 
compound levers operated by the same brake cylinder, each 
compound lever consisting of four simple levers. The first of 
these is called the cylinder lever; the second, the floating lever; 
the third, the truck live lever; while the fourth is called the truck 
dead lever. The fulcrum of each lever is marked F, and the 
points at which the power and weight are applied are marked P 
and Wj respectively. The right and left cylinder levers are of 
the first and third classes, respectively; the floating levers are 
of the third class; while the truck live levers and truck dead 
levers are of the first and the second class, respectively. The 
brake cylinder is assumed to exert 4,700 pounds pressure in an 
emergency application. 

Calculating the Power of the Hodge System. — To calculate the 
power applied to the brake shoes, it is now simply a question of 
using the proper rules for the separate levers. For the first, or 
cylinder lever, P = 4,700; therefore, 

w 4,700 X 15 . 

W = — -= = 4,700 pounds, 

and this is the force applied to P of the floating lever. 

The pressure on the fulcrum F of the cylinder lever is equal 
to the sum of P and W, or 9,400 pounds (see Art. 60). P of 



54 THE AIR BRAKE. §3 

the floating lever is 4,700, as already remarked; therefore, 

u/ 4,700 X 18 _ Q _ n , 

W = — — ^ = 2,350 pounds, 

and the pressure on F of this lever is 4,700 — 2,350 = 2,350 
pounds. P of the truck live lever is 2,350 pounds; therefore, 

T „ 2,350X24 Q . AA , 

W = — ^ = 9,400 pounds, 

and the force applied to the wheels at F is 9,400 + 2,350 
= 11,750 pounds. P of the truck dead lever is 9,400; hence, 

■ 9,400X25 ., __ , 

W = — — ^r — 11,750 pounds, 

the force applied to the wheels, while the force exerted at the 
fulcrum i^is 11,750 — 9,400 = 2,350 pounds. 

The calculations for the left-hand compound lever are made 
in the same way, beginning with 9, 400 .pounds applied to P of 
the cylinder lever. 

We may remark here that the truck live lever L may also be 
regarded as a lever of the second class, the relative positions of 
power, weight, and fulcrum then being .as noted in Fig. 8. If 
we have in mind the exerting of a force on shoes S, then the 
end A of lever L must be regarded as the fulcrum. If, on the 
other hand, we are considering the exerting of a force on 
the shoes S', then the point of contact of S on its wheel becomes 
the fulcrum. Thus, the lever L is, at one and the same time, a 
lever of the first or the second class, according to the point of 
view we take, that is, whether we are considering the question 
of exerting a pressure on S or on S'. In either case, of course, 
the numerical results are the same. 



66. The Stevens System. — The Stevens system of car- 
brake levers is shown in diagram in Fig. 16. It will be noticed 
that in this system there are no floating levers, the cylinder 
levers being lengthened sufficiently to allow the weight arm to 
be coupled directly to the truck live lever. It will be npticed, 
also, that all of the simple levers are of the first class, except 
the left-hand cylinder lever, which is of the third class, and the 
two truck dead levers, which are of the second class. 



§3 THE AIR BRAKE. 55 



Calculating the Power of the Stevens System. — To calculate the 
power applied to the brake shoes in this system of levers, 
proceed as with the- Hodge system, bearing in mind what was 
said in Arts. 59 and 60. For example, if the brake cylinder 
exerts a force of 4,700 pounds, a force of 

4,700 X 15 Q _ n 

- — stj *= 2,350 pounds 

will be exerted at W of the cylinder lever, while the force F on 
the fulcrum will equal 4,700 + 2,350 == 7,050 pounds. 2,350 
pounds applied to P of the truck live lever will cause a force of 

2,350 X 24 Q , m , 

-i — = 9,400 pounds 

to be exerted at W, while the force on the fulcrum F (the 
brake shoes) will be 9,400 + 2,350 = 11,750 pounds. With a 
force of 9,400 pounds exerted at P of the truck dead lever, 
a force of 

TT . 9,400X30 _ _ n , 

W = — — yj == 11,750 pounds 

will be applied to the brake shoes, while the fulcrum F will be 
subjected to a force of 11,750 — 9,400 = 2,350 pounds. The 
force applied to the other brake shoes can be found in a 
similar manner. 

As regards the leverage of the truck live lever, the last para- 
graph of Art. 65 applies here also. 

67. Cam Driver-Brake. — The following very simple 
method for determining the braking power developed by a 
cam driver-brake was invented by Mr. H. A. Wahlert, of 
the American Brake Company: 

Take two pieces of wire of the same diameter and place them 
between the top and bottom toes of one of the brake shoes and 
the wheel; then apply the brakes fully and measure the piston 
travel. Next, release the brakes, recharge fully, and again 
appty the brakes in full with the wires removed. Measure the 
piston travel and find how much it increases when the wires 
are removed. The wires are used to find the relative amount 



56 



THE AIR BRAKE. 



§3 



of travel of the weight arm (the brake shoe) and power arm 
(the piston); by subtracting the amount of piston travel when 
the wires are in place from the amount when they are removed, 
the distance the piston travels while the brake shoe travels the 
thickness of the wire can be determined. Knowing the relative 
travel of the brake shoe and piston, and the force developed 
by the cylinder, the force exerted on one brake shoe can be 
determined by rule II, Art. 58. The rule, as applied to this 
case, may be stated as follows: The force exerted on one brake 
shoe of a cam driver-brake is found by multiplying the increase of 
piston travel (determined as above) by the force developed in 
the brake cylinder (in pounds), and dividing the result by the 



P = 7000 




F = 7000 



W-2S000 W- 21000 W^ 14000 




F=7000 F=7000 F=7000 

Fig. 17. 



TT= 7000 



diameter (in inches) of the wire used. To find the total force 
exerted on the four shoes, multiply this amount by 4. 

As an example of the use of this rule, suppose the diameter 
of the wires used to be -J- inch, the piston travel with the wires 
inserted to be 4 inches, and when removed, 4^ inches. In this 
case the increase in piston travel would be 4^ — 4 = -| inch. 
Then, if a total force of 2,500 pounds were developed by the 
brake cylinder, the force exerted on each brake shoe would be 



W = 



2,500 Xi 



10,000 pounds. 



This would give a total force on the four shoes of 4 X 10,000 
= 40,000 pounds. 



§3 THE AIR BRAKE. 57 

68. American Outside Equalized Brake. — This type 
of brake was illustrated in Fig. 2, Art. 55, and a diagram of it, 
as applied to an engine having four pairs of drivers, is given in 
Fig. 17. In a brake of this kind, the levers are so proportioned 
that the braking power developed at the brake cylinder is 
distributed equally among the drivers, the force applied to the 
different brake shoes being maintained equal; hence, the brake 
is said to be an equalized brake. 

In the figure, the cylinder lever is of the first class, while the 
others are of the third class, the relative lengths of the lever 
arms being given in each case. The total force developed in the 
brake cylinder is, say, 7,000 pounds. This will cause a force of 

7 '°°; X5 = 35,000 pounds 

to be exerted at P of lever A, which in turn will cause a force of 
W = ^00X4 = 28)()00 poundg 

O 

to be exerted at P of lever B. The force applied at the fulcrum 

(the brake shoes) of lever A is 35,000 — 28,000 = 7,000 (see 

Art. 60). 28,000 pounds at P of lever B will exert at P of 

lever C a force of 

TJ/ 28,000 X 3 nnn " 

W = — - — j = 21,000 pounds, 

and a force of 28,000 — 21,000 = 7,000 pounds will be exerted 
at the fulcrum (brake shoes) of lever B. A force of 

TJ/ 21,000X2 1>|nnn , 

W = — - — s = 14,000 pounds 

will be exerted at P of lever D, while 21,000 — 14,000 = 7,000 
pounds will be exerted on the shoes of lever O. 14,000 pounds 
at P of lever D will exert a force of 

14,000 XI 
W = > — = 7,000 pounds 

at the shoes, and 14,000 — 7,000 = 7,000 pounds at the 
fulcrum F. 



58 THE AIR BRAKE. §3 



For an engine having two pairs of drivers, the end W of the 
cylinder lever would be connected at P of lever C, and levers A 
and B would not be used. A force of 21,000 pounds would 
have to be exerted by the cylinder lever to give 7,000 pounds 
at each brake shoe, so that if the same size cylinder were used, 
the power arm of the cylinder lever would have to be three 
times as long as the weight arm. 

On an engine having three pairs of drivers, the cylinder lever 
would be connected to the lever B, and would have to exert 
28,000 pounds to give 7,000 pounds at each brake shoe; hence, 
if the brake cylinder were of the same size as that just consid- 
ered, the power arm of the cylinder lever would have to be four 
times as long as the weight arm. 



BRAKE POWER. 



PRESSURES APPLIED TO BRAKE SHOES. 

69. In Art. 45 the statement was made that if the 
frictional resistance exerted between the wheel and the shoe 
were greater than that exerted between the wheel and the rail, 
the wheel would slide. With a good rail, these frictional 
resistances will be practically equal when the force applied at 
the brake shoe is equal to the pressure of the wheel on the rail, 
so that the force applied to the brake shoe must be less than 
the pressure of the wheel on the rail, to insure the wheel 
against slipping when used under the varying conditions of 
service. Practical experience has demonstrated that the best 
results will be obtained by the use of the following as the 
maximum safe pressures on the brake shoes in the different 
classes of service: For passenger cars, T 9 ¥ , or 90 per cent., of 
the weight on the rail under the wheel when the car is empty; 
for freight cars, T 7 -g-, or 70 per cent., of the weight on the rail 
when the car is empty; for tenders, 100 per cent., or the entire 
weight on the rail when the tender is light; for driving wheels, 
t 7 -q 5 ¥ , or 75 per cent. , of the weight under the drivers when the 
engine is ready for the road. 



§3 THE AIR BRAKE. 59 



CALCULATION OF BRAKING POWER. 

70. The method of calculating the proper braking power to 
use in any case is as follows : First find the weight on the rail 
under each wheel, b} 7- dividing the entire weight of the empty 
car by the number of wheels. Then, if the car is a passenger 
car, take t 9 -q of this, or, if a freight car, take ■£$, as the maximum 
force to be used on each brake shoe. In other words, this is 
the allowable force per shoe; therefore, the total braking force 
can be found by multiplying this amount by the number of 
wheels that are fitted with brakes, and from this the proper 
proportion of brake levers can be determined. 

The sizes of brake cylinders that are used on cars and tenders 
of different weights are as follows: 6-inch brake cylinders are 
used on freight cars having a light weight of 15,000 pounds or 
less; 8-inch cylinders on tenders of 35,000 pounds light weight 
or less, and also on freight cars whose light weight is between 
15,000 and 42,000 pounds; 10-inch cylinders on tenders of 
over 35,000 pounds light weight, and also on passenger cars 
of 50,000 pounds or less; 12-inch cylinders on passenger cars 
whose light weight is between 50,000 and 70,000 pounds; and 
14-inch cylinders on passenger cars of over 70,000 pounds. 

Example. — What is the maximum braking power that should be 
allowed at each brake shoe of a 72,000-pound passenger ear having 
6- wheeled trucks, 4 wheels only of each truck being supplied with 
brakes? Also, what will be the total braking force? 

Solution. — If this car weighs 72,000 pounds and has 12 wheels, there 

72 000 
will be a pressure of — ~- = 6,000 pounds on the rail under each 

wheel; hence, the highest allowable braking force per wheel should 
be .9 X 6,000 = 5,400 pounds. The total allowable braking force of 
the car, therefore, will be 8 X 5,400 = 43,200 pounds, since only 
8 wheels are braked. 

71. The Force Exerted in the Brake Cylinder. — The 

total allowable braking force should not be exceeded when an 
emergency application of the brakes is made, since at such 
times it is especially important that no wheels slide, as a sliding 
wheel exerts but little retarding force. For this reason, the 



60 



THE AIR BRAKE. 



§3 



braking power is calculated on the assumption that, in an 
emergency application, 60 pounds pressure is obtained in the 
brake cylinder with a quick-action brake, and 50 pounds with 
a plain triple. 

The total force in pounds that a brake cylinder will develop 
when subjected to 50 and 60 pounds pressure per square inch, 
has been calculated for several sizes of cylinders, and the results 
tabulated as follows: 

FORCE EXERTED IN BRAKE CYLINDER. 



Size of Cylinder. 
Inches. 


With 50 Lb. 
Pressure. 


With 60 Lb. 
Pressure. 


6 


1,400 


1,700 


8 


2,500 


3,000 


10 


3,900 


4,700 


12 


5,600 


6,800 


14 


7,700 


9,200 



The force exerted in a brake cylinder is found by multiplying 
the area of the piston in square inches by the pressure per 
square inch in the cylinder. Thus, if the piston has an area of 
154 square inches, it will develop a force of 154 X 50 = 7,700 
pounds under a 50-pound pressure. 

The area of the piston may be found by multiplying the 
diameter of the piston (in inches) by itself, and by 11, and 
dividing the product by 14. Thus, the area of a 10-inch piston 

- = 78^- square inches, about. The areas of 



is 



14 



various sizes of pistons used in the brake system are as follows: 
28 \ square inches area in a 6-inch piston, 50J- in an 8-inch, 
78 J in a 10-inch, 113 in a 12-inch, and 154 in a 14-inch, piston. 
Another, and slightly more accurate, method of calculating 
the area of a piston is to multiply the diameter (in inches) by 
itself, and the product by .7854. 



The Air Brake 

(PART 4.) 



TRAIK AIH-Sia^ALI^G SYSTEM, 



GENERAL ARRANGEMENT OF APPARATUS. 

1. The general arrangement of the train air-signaling 
apparatus on an engine, tender, and passenger car is shown in 
Figs. 1 and 2. This system has gradually taken the place of 
the old bell-cord-and-gong method of signaling on passenger 
trains, on account of the ease and certainty with which signals 
can be transmitted to the engineer from any part of the train. 

The engine, tender, and each of the cars are piped with a 
f-inch pipe, which is connected between cars by means of hose, 
so that when all the hose is coupled, the signal-pipe line extends 
throughout the entire train. 

A car discharge valve, Fig. 1, is provided on each car. This 
is usually located outside the car above the door, as shown in 
the figure, and is piped to the train signal pipe. Sometimes, 
however, it is placed inside the car above the door, to guard 
against the valve being clogged in winter. The former position 
is preferable, however, as the chances of clogging are small, and 
the annoyance caused by the sharp sound of discharging air 
every time the valve is opened to make signals is avoided. 

A signal cord is attached to the lever of the discharge valve, 
and one end extends across the platform and is fastened in a 
suitable manner to the hood, while the other end extends 
through the car and is fastened to the hood on the other end of 
the car. This cord enables the discharge valve to be operated 
from any part of the car. 



THE AIR BRAKE. 



§4 



The air-signal apparatus on the engine, Fig. 2, consists of 
the signal valve, signal ivhistle and pressure-reducing valve. A 
f-inch pipe leads from the main reservoir to the reducing valve, 
and thence leads to, and connects with, the T- fitting s in the 




signal pipe. Air from the main reservoir can thus pass through 
the pressure-reducing valve and thence into the signal pipe and 
signal valve, but at a reduced pressure. A pressure of 40 
pounds with the improved valve, and 25 with the old valve, is 



THE AIR BRAKE. 



usually maintained in the signal system, and the duty of the 
reducing valve is to diminish the pressure from 90 pounds 




(main-reservoir pressure) down to the required pressure for 
use in the signal system. 



THE AIR BRAKE. 



The signal whistle, Fig. 3 (a small 
whistle located in the cab, as close to the 
engineer as practicable), is piped to the 
signal valve, and it is the operation of 
the latter that causes the whistle to blow. 

When the conductor wishes to transmit 
a signal to the engineer, he gives the signal 
cord in one of the cars a pull. This opens 
the car discharge valve on that car and 
allows some of the air in the main signal 
line to escape to the atmosphere, thus redu- 
cing the signal-pipe pressure. The reduction 
in pressure operates the signal valve on the 
engine, which, consequently, discharges a 
small quantity of air through the signal 
whistle in the cab, thus causing it to sound 
a short blast. Each time the cord is pulled, 
the signal whistle gives a blast. 




Fig. 3. 



DESCRIPTION OF APPARATUS. 



REDUCING VALVE (OLD STYLE). 

2. Although this style of reducing valve, Fig. 4, has 
been superseded to a great extent by the improved valve, there 
are still a sufficient number in use to warrant a description of 
them being given here. 

The main-reservoir connection is made at X, while a pipe 
leads from Y to the signal pipe. 4 is the supply valve that 
regulates the admission of air to the signal system; it is 
operated by the stem of the reducing-valve piston 8 and by 
the supply- valve spring 10. 7 is the rubber diaphragm; 6, the 
diaphragm ring; and 9, the regulating spring. In this style of 
valve, the spring 9 was made strong enough to just resist a 
pressure of 25 pounds per square inch in chamber B. In some 
instances, however, it has been replaced by a spring that 
requires 40 pounds pressure per square inch to compress it. 
The outlets e, e, in the cap 3 prevent air (due to leakage) 



§4 



THE AIR BRAKE. 



from accumulating back of the piston and piston stem and 
rendering the valve inoperative. 




3. Operation of Valve. — The operation of this valve is 
as follows: The spring £, acting on the piston 8, causes the 
stem of the piston to hold supply valve 4 from its seat, so that 



6 THE AIR BRAKE. 



main-reservoir air entering at X is free to pass through the 
passages 2, 2, past valve 4 and into chamber B, and thence 
through the outlet Y to the signal line. This increases the 
pressure in the signal pipe and chamber B until it reaches 
25 pounds per square inch, when the diaphragm 7 and piston 8 
are forced upwards against the action of the spring 9. The 
supply- valve spring 10 then forces the supply valve to its seat, 
and prevents the further passage of air from the main reservoir 
to the train pipe. As long as the pressure in chamber B 
remains at 25 pounds, spring 9 will be compressed and the 
supply valve will remain closed. Any reduction of pressure in 
chamber B, however, will cause the regulating spring to force 
the diaphragm 7 and piston 8 downwards, thus forcing the 
supply valve from its seat and allowing, sufficient air to pass 
to the signal pipe to again raise its pressure to 25 pounds, 
when the supply valve will close. The old-style valve has no 
regulating nut by means of which the tension of the regulating 
spring can be adjusted to alter signal-pipe pressure. If it is 
necessary to increase the signal-pipe pressure, the regulating 
spring 9 will have to be replaced by one that is stiff er; or a 
couple of washers may be placed in the cap nut, the effect of 
which will be to compress the spring more, and thus make it 
offer a greater resistance to the upward -motion of piston 8. 



REDUCING VALVE (IMPROVED). 

4. The improved reducing valve is shown in Fig. 5; 

2 is a plug cock which, in the position here shown, is allowing 
air to enter the reducing valve, but, when turned at right 
angles to its present position, cuts the valve out of service; 

3 is the lower cap; 4, the supply valve; 5 ? the supply- valve cap 
nut; 6, the supply-valve spring; 7, the reducing-valve piston; 
8, a rubber diaphragm consisting of two pieces of rubber; 9, the 
regulating spring; 10, the diaphragm ring; 11, the piston pack- 
ing-ring (which, together with the diaphragm, serves to prevent 
leakage of air past piston 7); 14, the regulating nut by means 
of which the tension of the spring 9 is adjusted; and 15, the 



§4 



THE AIR BRAKE. 



check-nut. The passage e is to allow any air leaking past the 
piston 7 to escape to the atmosphere. 

5. Operation of Valve. — The tension of the regulating 
spring 9 is adjusted to just withstand a pressure of 40 pounds 




Fig. 5. 



per square inch in chamber B. When the pressure is less than 
this amount, the spring 9 forces piston 7 upwards and the 
piston stem unseats the supply valve Jf. Main-reservoir air 
(entering at X) is then free to pass through the plug cock #, 



8 



THE AIR BRAKE. 



§4 



supply valve 4, and thence out through Y to the signal pipe. 
As soon as the pressure in the signal pipe and chamber B 
reaches 40 pounds, piston 7 is forced downwards and the spring 
6 then forces the supply valve to its seat, closing communica- 
tion between the main reservoir and the signal pipe. Any 
reduction in signal-pipe pressure will allow the spring 9 to force 
piston 7 upwards, thus opening the supply valve again. The 
valve then remains open until the signal-pipe pressure is again 

raised to 40 pounds, when it closes. 
The reducing valve should be 
placed in the cab, in some mod- 
erately warm place, if possible, so 
as to prevent its freezing in cold 
weather. 

With the improved valve, the 
signal- pipe pressure may be in- 
creased by screwing up the regu- 
lating nut 14-, or decreased by 
unscrewing this nut. 




CAR DISCHARGE VALVE. 

6. A sectional view of the car 
\~s 1 j " discharge valve is shown in 

Fig. 6, in which 3 is the discharge 
valve, and 4 the discharge- valve 
spring that holds this valve up 
against its seat. 5 is the lever or 
handle to which the signal cord is 
attached, while 6, 6 are stop-pins. 
There is a union connection at a 
to which the branch pipe from the 

signal pipe is connected, while the exhaust port b leads to the 

atmosphere. 



7. Operation of Valve. — When the signal cord on either 
side of the discharge valve is pulled, the lever 5 is caused to 
strike the stem of the discharge valve 3 and force the valve 



§4 THE AIR BRAKE. 



from its seat. Air from the signal pipe then passes up through 
the branch pipes and out to the atmosphere through the union 
connection a and the port b, causing a reduction in signal-pipe 
pressure. As soon as the signal cord is released, the spring 4 
forces the discharge valve to its seat again and stops the dis- 
charge of air from the signal pipe. 

Referring to Fig. 1, it will be seen that the branch pipe to 
the discharge valve is supplied with a strainer (where it con- 
nects with the main signal pipe) and a cut-out cock, the former 
to prevent dirt from reaching the discharge valve, and the latter 
to enable the discharge valve to be cut out in case it is disabled. 
The handle of the cut-out cock stands parallel with the pipe 
when the discharge valve is cut out, and at right angles to it 
when cut in. Also, the cut-out cocks in the signal pipe on 
either side of the signal hose are closed when the handles stand 
parallel with the pipe, and open when at right angles to it. 



THE SIGNAL VALVE. 

8. The signal valve, Fig. 7, is located under the foot- 
board of the cab, and may be placed either on the engineer's 
or the fireman's side. The signal pipe is connected to it at X, 
while a pipe leads from Y to the signal whistle. The valve 
body is divided into two chambers A and B by the rubber 
diaphragm 12, which also is attached to and operates the dia- 
phragm stem 10. This stem extends through the bushing 9, 
and its end forms a valve (with seat in bushing 7) that con- 
trols the passage e leading to the whistle. A small portion of 
the stem 10 fits the bushing 9 rather snugly, while below this a 
groove/ is cut around the stem. Below this groove the stem is 
milled out so as to have a cross-section like that shown at x. 

9. Operation of Valve. — When the signal pipe is being 
charged, air enters the signal valve at X, and, passing through 
the small port d, charges chamber A. It also passes through 
the passage cc, and feeds up slowly past the stem 10 into 
chamber B, charging this to the same pressure as chamber A. 
The pressures in chambers A and B and the signal pipe are 
equal when the pipe is fully charged. 



10 



THE AIR BRAKE. 



When the signal cord is pulled and a reduction is made in 
the signal pipe, it causes a reduction of pressure in the signal 
valve also; but, since the stem 10 makes a rather snug fit, the 
pressure in chamber A above the diaphragm reduces faster 
than the pressure in chamber B; consequently, the diaphragm 
is forced upwards, and raises the stem 10, thus opening the 




exhaust valve in 7. The stem 10 is lifted until the groove / is 
above the bushing 9, when the air in chamber B escapes quickly 
through the groove /, the milled spaces in the stem 10, and 
the passage e, out to Y and the whistle, causing the latter to 
give a blast. Air also escapes from chamber A to the whistle, 
through the passages cc and e. 

The same reduction of pressure that operates the signal valve 
also opens the reducing valve, allowing air from main reservoir 
to flow into, and raise the pressure in, the signal line. This 
increase of pressure, following the closing of car discharge valve, 



§4 THE AIR BRAKE. 11 

and immediately after the reduction in signal valve, increases 
the pressure in chamber A faster than in chamber B, thus 
forcing the diaphragm downwards, closing the valve leading to 
passage e, and stopping the blast of the whistle. 

SIGNALING. 

10. In transmitting signals by means of the air- 
signaling system, certain precautions must be observed in order 
to obtain good results. For each blast of the whistle, the car 
discharge valve should be held open just long enough to reduce 
the pressure in the signal pipe clear up to the signal valve on 
the engine, when it' should be closed. It should then be 
allowed to remain closed until the pressure has equalized 
throughout the system, before it is again opened to transmit 
another signal. If the discharge valve is opened a second and, 
possibly, a third time before the whistle has ceased to blow due 
to the first reduction, the whistle will give one long blast instead 
of two or three short ones, as intended. If it is opened a 
second time before the pressure has fully equalized in the signal 
pipe, the whistle will give a blast after each discharge, but the 
last blast will be weak on account of the pressure being less 
than 40 pounds. 

In transmitting signals, the best results will be obtained if 
the car discharge valve is allowed to remain closed from 2 to 
3 seconds between blasts, depending on the length of the train. 
In other words, for each blast, pull the signal cord straight down- 
wards and hold the discharge valve open for 1 second; then 
allow from 2 to 3 seconds for the pressure to equalize through- 
out the signal pipe before it is again opened for another blast. 



DEFECTS IN THE SIGNALING SYSTEM. 

lie Although there are but comparatively few parts in the 
air-signaling system, it requires good judgment to locate defects 
that cause incorrect signals to be given. Also, it should be 
borne in mind that it is not so much the amount of the 
reduction as the rapidity with which it is made, that causes 
the whistle to blow. 



12 THE AIR BRAKE. §4 



SIGNAL PIPE FAILS TO CHARGE. 

12. If it is found that no air passes into the signal pipe, 
first see whether the cocks on each side of the hose between the 
tender and train have been opened. If so, the opening in the 
plug 16 of the reducing valve, Fig. 5, may be stopped up with 
oil and dirt; or the lining in the hose may be loose and block- 
ing the passage; or, if the weather is cold, the signal pipe on 
the engine or tender may be stopped up with ice, or the 
reducing valve may be frozen up. 



XO EXHAUST FROM DISCHARGE VALVE. 

13. If no exhaust occurs at the discharge valve when the 
signal cord is pulled, the signal pipe being properly charged, the 
trouble may be due to the cut-out cock, Fig. 1 (usually placed 
in the saloon), being turned so as to cut out the discharge valve. 



WHISTLE PAILS TO BLOW. 

14. If an exhaust occurs at the discharge valve when the 
signal cord is pulled, but the signal whistle fails to give a blast, 
the trouble may be due to the strainer in the T, where the 
branch pipe connects with the signal pipe, being stopped up 
(see Fig. 1). In this case, the exhaust may sound all right, 
since there is considerable air in the branch pipe between the 
strainer and the discharge valve', but the air in the main pipe 
cannot get past the strainer fast enough to make a sufficiently 
quick reduction to operate the signal valve. If the trouble is 
not in the strainer, it may be that (1) port d of the signal valve 
is stopped up, in which case no air can enter the valve to 
charge it; (2) stem 10 of signal valve has worn sufficiently 
loose in bushing 9 to allow pressure in chamber B to reduce 
about as fast as that in chamber A; (3) the signal- valve 
diaphragm is bagged or, possibly, cracked; (4) the bell of the 
signal whistle is imperfectly adjusted or its bowl is full of dirt; 
(5) whistle is so situated that wind blowing across the bowl 
prevents it from sounding; or (6) dirt in port of bushing 7. 



§4 THE AIR BRAKE. 13 

If poor rubber is used in the diaphragm, or if oil gets on it, 
the rubber will, in time, stretch and bag. In that event, when 
a signal-pipe reduction is made, the diaphragm will respond to 
it without raising the stem 10 from its seat in 7, and no blast 
will result. An overheated air pump also tends greatly to heat 
the rubber and buckle or distort the diaphragm. In some cases, 
the diaphragm cracks, causing chambers A and B to become 
directly connected. 

WHISTLE GIVES ONE LONG BLAST. 

15. If, in transmitting a signal, the whistle simply gives 
one long blast, it may be due either to the reductions being 
made too close together, or to the diaphragm stem 10 of the 
signal valve working stiffly in the bushing 9, in which event 
the passage at e would remain open until a sufficient difference 
of pressure existed in chambers A and B to force the stem 
10 to its seat. 



WHISTLE BLOWS WHEN BRAKES ARE RELEASED. 

16. If the whistle blows every time the brakes are released, 
it indicates that there is direct connection between the main 
reservoir and signal pipe, and that the latter is charged to main- 
reservoir pressure. This may be due either to valve 4- of the 
reducing valve being held open by dirt on its seat, or to there 
being too much tension in the spring 9; or, in the old-style 
reducing valve, Fig. 4, to the spring 10 being broken or too 
short, so that it does not force valve If. to its seat. 

The reason why the whistle blows when the brakes are 
released is as follows: Since there is a direct opening between 
the signal pipe and the main reservoir, air will flow from the 
former to the latter every time the main-reservoir pressure is 
reduced in releasing the brakes. This causes a reduction of 
signal-pipe pressure right at the signal valve, which, if the 
opening through the reducing valve is large enough, and 
the main-reservoir pressure is reduced sufficiently fast, will 
operate the signal valve and cause the whistle to give a blast. 
If the opening through the reducing valve is small, the whistle 



14 THE AIR BRAKE. §4 

may not sound if the signal pipe is long, whereas it may do so 
on a very short train or on a lone engine. 

Main-reservoir pressure in the signal pipe can be detected 
from the train by a stronger discharge of air from the discharge 
valve when the signal cord is pulled; on the engine it will be 
indicated by the signal whistle screeching, due to the fact that 
the bell of the whistle is adjusted for 40 pounds pressure and 
not for 90. 

OTHER DEFECTS. 

IT. Sometimes the whistle only gives a weak blast when the 
cord is pulled. This may be due to the regulating spring of 
the reducing valve being too weak, so that there is less than 
40 pounds in. the signal pipe; the whistle may be full of 
dirt or be improperly adjusted; or the passage through the 
bushing 7 in the signal valve, Fig. 7, may be partly stopped 
up with oil and dirt. 

The bell of the signal whistle, Fig. 3, may be adjusted by 
loosening the locknut n and unscrewing or screwing up the bell, 
as the case may require. 

If, in the signal valve, Fig. 7, the valve formed by the end 
of the stem 10 leaks or is held from its seat on bushing 7 by 
dirt, there will be a constant blow at the whistle that will 
produce a singing noise. 

A leaky car discharge valve, due either to dirt on the seat of 
the valve or to a defective valve seat, is a common source 
of trouble. If dirt on the valve seat is the cause of the leak, 
opening and closing the valve will sometimes remedy it by 
blowing the dirt off. 

The accuracy with which signals can be transmitted depends, 
to a considerable extent, on the fit of the stem 10 in the bush- 
ing 9. If it makes too tight a fit, the whistle will give one 
long blast instead of the usual short ones, as already explained. 
Also, signal-pipe leakage is liable to operate the signal valve and 
cause the whistle to sound a blast, and the signal valve will not 
respond to a short, quick reduction. 

If the fit of the stem is too loose, the signal valve will not be 
affected by leaks; neither will it respond to a light, quick 



THE AIR BRAKE. 15 



reduction in signal pressure. Also, when the train is short, the 
signal valve will respond to a reduction made on any of 
the cars in the train, but, on a long train, a reduction from the 
rear cars may not be sufficiently rapid at the signal valve to 
operate the valve, and the whistle will not sound. Then, again, 
the whistle is liable to give two or three blasts when the cord 
is pulled, if the stem is too loose. This is brought about as 
follows: When this cord is pulled, a reduction is made in the 
signal valve above the diaphragm, which causes the diaphragm 
to be raised, thus allowing air to escape from chamber B (below 
the diaphragm) to the whistle, causing it to give a blast. The 
reducing valve being opened by same reduction, admits air into 
signal pipe and chamber -A, causing the valve to seat in bush- 
ing 7 before pressures above and below diaphragm equalize. 
When the stem fits properly, the pressure in the chamber above 
the diaphragm increases much faster than that in the chamber 
below it; hence, the diaphragm is held down and a second blast 
does not occur. When the stem fits loosely, however, both 
chambers charge at more nearly the same rate, and, the dia- 
phragm being in a state of vibration, the rapid increase of pres- 
sure below the diaphragm will cause it to rebound, as it were, 
thus raising the stem and causing the signal whistle to give a 
second blast. In case the signal whistle gives two blasts when 
the cord is pulled, it can be remedied by lowering the stem 10 
in the bushing 9. The length of fit of the stem in its bushing 
should never be less than -fa inch, nor more than ^ w inch, 
measuring from the top of groove / to the top of bushing 9. 



TERMINAL TEST OF AIR-SIGNAL APPARATUS. 

18. In making up a train, the air-signal hose should be 
connected up at the same time the train-line hose is, and all the 
signal-line cocks opened except the rear cock on the last car of 
the train; this should be closed, and the signal hose hung up 
properly. While looking the train over for leaks, the signal 
hose and couplings and also the car discharge valves should be 
inspected to see if they are in good condition. If a discharge 
valve is found to be leaking, jerk it open a few times; if this 



16 THE AIR BRAKE. §4 



does not remedy the leak, the valve will have to be reseated 
with a new gasket. If a discharge valve is found to be defect- 
ive while on the road, it should be cut out by closing the cut- 
out cock in the branch pipe. The conductor should then be 
notified, and he should report the same for repairs at the end of 
the run. In testing the signal system, signals should be trans- 
mitted from the rear car of the train, from a car in the center, 
and also from the car next to the engine. 



TESTING DEVICE. 

19. The device about to be described has been used very 
successfully in testing for, and locating, defects in the signaling 
apparatus, and it ought to be more widely used than it is. It 
consists simply of an air gauge, a single-line hose, and a small 
petcock, the cock having a -J-inch hole through its plug. The 
hose is fitted with a coupling, but has no nipple, the air 
gauge being connected to its nipple end. A hole is drilled 
through the coupling into the air space and tapped, and the 
petcock screwed into it. 

When this device is coupled into the signal pipe, the signal- 
pipe pressure will be indicated by the air gauge, while, by means 
of the petcock, a reduction of any amount or duration may be 
made in the signal-pipe pressure. 

20. Using the Device. — The testing device may be 

used to determine the condition of the automatic reducing 
valve, as follows: First connect the device into the signal pipe 
and charge the latter to standard pressure; then open the pet- 
cock wide, make a 10-pound reduction, and note the time 
required to raise the pressure to standard again. If the pressure 
rises slowly and the reducing valve is of the improved type, the 
passage through the valve is probably reduced by gum and 
dirt, and the valve should be thoroughly cleaned. If the 
reducing valve is of the old style, it may be that the supply 
valve does not open sufficiently to admit of its feeding faster, 
and the valve should be taken down and repaired. 

To test the signal valve make a slow, gradual reduction of 
about the same magnitude as the leaks in the signal pipe would 



§4 THE AIR BRAKE. 17 

amount to; then gradually increase the rate of discharge until 
the signal whistle blows. If the whistle blows when a slow, 
gradual reduction is being made, it indicates that the stem 10 
makes too tight a fit in the bushing 9, and that the pressure on 
the under side of the diaphragm cannot escape as the pressure 
above is reduced. The consequence is that the pressure in 
chamber B raises the diaphragm as soon as a sufficient differ- 
ence of pressure is established between the chambers on either 
side of the diaphragm, and air discharges into the whistle, 
causing it to sound. If the whistle blows when a quick, heavy 
reduction is made, but will not do so with a quick, light reduc- 
tion, the indications are that the stem 10 fits too loosely in 
the bushing 9. 

THE HIGH-SPEED BRAKE. 



HIGH-SPEED SERVICE. 

21. It is the average speed of a train between terminals 
that determines the service to which the train belongs. 
A high-speed train is one that makes a high average speed; 
hence the conditions of its operation must necessarily differ 
very materially from those of an ordinary express train. The 
express train may make an average speed of 35 to 40 miles an 
hour, while the average speed of the high-speed train may be 
60 miles or more. The express train may attain a maximum 
speed for a short distance that is considerably greater than that 
attained by the high-speed train, but certain parts of the run 
that are comparatively safe are chosen for these bursts of speed. 
The high-speed train, on the other hand, must maintain a high 
rate of speed throughout the run, regardless of whether passing 
through yards or over bridges, switches, etc., so that the chances 
of having to make emergency applications of the brake are 
much greater than in ordinary service. Also, it is much harder 
to stop a train when traveling at high speed, and a greater 
distance is necessary in which to do so. 

It has been found that, under the same conditions, the 
distance required to stop a train traveling at the rate of 40 miles 



18 THE AIR BRAKE. §4 

an hour is about twice as great as when traveling 30 miles; at 
50 miles an hour, between three and four times the distance 
is required; while at 60 miles, about five times the distance is 
necessary. Hence, since emergencies are more liable to occur 
with high speeds, and since the distance in which a train can 
be stopped increases very greatly with its speed, it has become, 
imperative that a more powerful brake than the quick-action 
one be employed on trains in high-speed service; the present 
high-speed brake is the direct result of this. necessity. 

The Westinghouse-Galton experiments, made in England in 
1878, and the more recent experiments of the Master Car 
Builders' Association of this country have demonstrated: (1) 
that the friction exerted between the wheel and the rail is prac- 
tically constant at all speeds; (2) that the friction exerted 
between the brake shoe and the wheel is very much less at high 
than at low speeds, being only J as great at a speed of 55 miles 
per hour as it is when the wheels are only just moving; (3) 
that on account of this reduction of frictional resistance at high 
speed, a considerably greater pressure can be applied to the 
brake shoe when the speed is high, without danger of sliding 
the wheels; and (4) that in order to make a brake shoe exert 
as great a retarding force at high as at low speeds, it must be 
subjected to a greater pressure at high speeds. 

The high-speed brake was made to conform with all these 
requirements, since it provides a very high cylinder pressure 
when the brake is first applied in emergency, and gradually 
reduces the pressure until it is low enough at slow speeds to 
avoid sliding the wheels. 



GENERAL ARRANGEMENT OF APPARATUS. 

CHANGES NECESSARY IN CAR EQUIPMENT. 

22. The general arrangement of . the apparatus of the 
high-speed brake on an engine, tender, and passenger car, is 
shown in Fig. 8. It is here seen that the apparatus and its 
general arrangement is practically the same as that of the quick- 
action automatic brake, but that the former contains a few 




TENDl 



\TIC PRESSURE 
'CtNG VALVE J Adjusted ro 
SOIbs. Pressure in Cylinder. 



?LE VALVE 




?EVER5INGC0CH. 

\ 



:oc«. 



COUPLING 




I AUTOMATIC PRESZUiE tLOnrr. 
f VALVE, Adjusted to retain SOI61 
t,Me Brake Cylinder. 



EN6UIE TRUCK BRAKE CrLINDER. 



FLEXIBLE HOSl I 



CP 




COUPLING 



DUPLEX G 



1T/C PRESSURE 

ICING VALVE, Adjusted to 

' GOibs. Pressure in Cylinder. 



CLE VALVE 



REVERSING COCK. 




COCK. 



§4 THE AIR BRAKE. 19 

pieces of apparatus not employed in the latter, these special 
pieces being shown heavily lined in the figure. For instance, 
the only difference in the equipment of a high-speed and a 
quick-action brake, as applied to a passenger car, is the addi- 
tion, in the former, of an automatic reducing valve, together 
with sufficient pipe to connect it to the brake cylinder. Also, 
in the high-speed brake every wheel on the car is fitted with 
the brake. 

A, Fig. 8, illustrates the use of a small safety valve that may 
be attached to extra cars not fitted with the regular automatic 
reducing valve when they are to be temporarily attached to 
high-speed brake trains. This valve is simply intended to tem- 
porarily take the place of an automatic reducing valve, and it 
should not be used as a permanent fixture. 



CHANGES NECESSARY IN ENGINE EQUIPMENT. 

23. General Remarks. — The chief changes necessary to 
transform the ordinary quick- action brake into a high-speed 
brake, are made in the engine equipment. In the first place, 
the engine- truck wheels, as well as the drivers, are supplied with 
brakes in the high-speed system, as, by so doing, a gain of about 
10 per cent, in the braking power can be made; this is not 
usually done with the quick-action brake. It will be observed 
that the engine-truck brake cylinder is connected with a flexible 
hose connection to its branch pipe. This is necessary, since the 
cylinder is fastened rigidly to, and therefore turns with, the 
engine truck. 

The engine is also supplied with a triple valve of special 
design that operates both the driver and engine-truck brakes, 
a cut-out cock in the branch pipe being necessary for the pur- 
pose of cutting out the valve in case of accident to driver brake. 
The engine-truck brake has a separate cut-out cock, so that it 
can be cut out without interfering with the driver brake. An 
automatic reducing valve is connected to the pipe that leads 
from the triple valve to the brake cylinders, thus performing 
the work of three separate reducing valves connected one to 
each brake cylinder. 



20 THE AIR BRAKE. §4 



In the tender equipment, a quick-action triple valve is used in 
place of the plain triple employed with the ordinary automatic 
tender brake, and an automatic reducing valve is attached to the 
tender cylinder. In order to attach the quick-action triple to 
the tender cylinder, it is necessary to use a special cylinder 
head, and, since the quick-action triple does not contain a cut- 
out cock, one must be placed in the branch pipe leading to it. 

24. Duplex Governor. — The ordinary form of pump 
governor is replaced by a duplex governor, and the feed- valve 
attachment on the brake valve is replaced with a pipe bracket 
that enables a duplex feed-valve attachment to be used. Both the 
duplex governor and duplex feed- valve attachment really con- 
sist of two ordinary instruments combined for the sake of 
cheapness and convenience, and each duplex instrument could 
be replaced with two regular instruments of the same kind. 
Both governors of the duplex pump governor are connected 
with, and are therefore operated by, main-reservoir pressure, 
since the pipe g leads to the main-reservoir connection on the 
brake valve. The regulating spring of one is adjusted to just 
withstand a pressure of 90 pounds per square inch on the 
governor diaphragm; the regulating spring of the other is 
adjusted for a higher pressure — about 120 pounds per square 
inch. A cut-out cock is placed in the pipe to the low-pressure 
governor, so that if the engine is to be used with a high-speed 
brake, it can be closed, thus cutting out the low-pressure 
governor and allowing the high-pressure one to govern the air 
pump. The cut-out cock is closed when the handle stands at 
right angles to the pipe, and open when the handle is parallel 
with it. If the engine is used with the ordinary quick-action 
brake, the cut-out cock is opened and the pump is then gov- 
erned by the low-pressure governor, as will be explained later. 

25. Feed Attachment. — The two valves of the duplex 
feed- valve attachment are adjusted for different pressures. 
The regulating spring of the one is adjusted so as to just with- 
stand a train-line pressure of 70 pounds per square inch, while 
the spring of the other is adjusted to about 110 pounds per 
square inch. The mechanism of each valve is exactly like the 



§4 THE AIR BRAKE. 21 



mechanism of the valve shown in Fig. 17, and explained in 
connection with the F-6 brake valve in Part 1. The feed-valves 
are secured to the body of the reversing cock, and the passage 
i of each is connected with the pipe b by means of a chamber 
in the reversing cock. Also, the passage /" of both valves is 
connected with the pipe a by means of another chamber, and 
the cock is so constructed that the right-hand feed-valve can be 
cut out of, or into, service by means of the handle h. When 
the engine is coupled to a train equipped with ordinary quick- 
action brakes, the feed valve that is adjusted to 70 pounds is 
used, and the other one is cut out. When the engine is coupled 
to a train equipped with the high-speed brake, the high- 
pressure feed valve is cut into service. 

There are two positions in which the handle h of the reversing 
cock may stand. The one shown is the position used when the 
engine is to be coupled to a train having the ordinary quick - 
action brake. In this position, the feed-valve that is adjusted 
for 110 pounds is cut out, and the train-line pressure is regu- 
lated to 70 pounds per square inch by means of the other feed- 
valve. If the engine is to be coupled to a high-speed brake 
system, the handle of the reversing cock is moved around to 
the right into the second position. This cuts into service the 
feed-valve that is adjusted for 110 pounds, and the train-pipe 
pressure is then regulated to that amount. This duplex feed- 
valve is usually placed under the running board of the engine. 



OPERATION OF APPARATUS. 



AUTOMATIC REDUCING VALVE. 

26. Description. — In Fig. 9 are given various sectional 
views of the automatic reducing valve, (a) representing 
a side view with half of the valve removed, while (6) is a 
horizontal cross-section taken through the slide valve, and 
viewed from above; (c), (r/), and (e) are rear views with the 
back portion of the upper half of the valve broken away so as 
to show in section the reducing-valve piston and slide valve, the 
section of the slide valve being taken through port b. 



22 THE AIR BRAKE. §4 

Referring to the figure, B is the bracket by means of which 
the valve is attached to the car or engine; 2, the valve body; 
3, the spring box; 4, the reducing- valve piston; 5, the piston 
packing- ring; 6, the piston stem; 7, the piston-stem nut; 
8, the slide valve; 9, the slide-valve spring; 10, the cap nut; 
11, the regulating spring; 12, the regulating nut and guide for 
piston 4', !&•> the check-nut; 14, a union stud; 15-16, a union 
connection; and 17, the strainer. The pipe to the brake cylinder 
connects with the valve at X, while the exhaust port Y leads to 
the atmosphere. Since the brake cylinder is connected at X, 
it is evident that the space within bushing d is always charged 
to the same pressure as the brake cylinder; hence, the slide 
valve 8 and the upper side of piston 4 are at all times subjected 
to brake- cylinder pressure also. A port c, views (a) and (6), 
passes through the slide valve from one side to the other; also, 
a triangular port b leads from port c to the face of the slide 
valve. A small port a passes through the seat of the slide valve 
and connects with the exhaust Y. In views (c), (d), and (e), 
the covered part of port a is represented by dotted lines. 

When the valve is used on a car, the regulating spring 11 is 
adjusted to just withstand a pressure of 60 pounds per square 
inch on the piston 4', when used on an engine, it is adjusted to 
withstand 50 pounds pressure. 

27. Operation of Valve. — Views (a) and (c) show the 
position of port a, with respect to port b of the slide valve, for 
all pressures under that for which the regulating spring is 
adjusted, which is usually 60 pounds. Port a is, of course, 
stationary; the slide valve 8, however, fits in between the 
shoulders of the piston stem 6, and is operated thereby; hence, 
port b moves up and down with the piston. 

As long as the cylinder pressure remains less than 60 pounds 
per square inch, the reducing valve plays no part in an ordi- 
nary service application of the brake, the valve remaining in 
its normal position, with port a blanked, views (a) and (c). 
Suppose, though, that in making a service application, the brake- 
cylinder pressure should increase above 60 pounds; in that 
event, the pressure above the piston 4 would be sufficient to 



Exhaust 




Fig 




Service, -Pressure Exceeding GO Pounds 




Fig. 10. 



§4 THE AIR BRAKE. 23 



compress the regulating spring, and the piston and slide valve 
would be forced downwards until ports a and b assumed the 
position shown in view (d). In this position, brake-cylinder 
air is free to flow to the atmosphere through the ports c, b, and 
a, until the pressure is reduced to 60 pounds, when the regu- 
lating spring forces the piston and slide valve upwards into their 
normal position again. View (d) therefore shows the relative 
positions of ports a and b in a service application during the 
time the brake-cylinder pressure exceeds 60 pounds. The area 
of the opening through ports a and b in this position is such 
that air can discharge from the cylinder as fast as it enters 
through the service port in the slide valve of the triple. 

The relative positions of ports a and b in an emergency appli- 
cation of the brake is shown in view (e). Here, air enters the 
brake cylinder from the train line and auxiliary reservoir in 
much greater volume than it could possibly escape through 
the ports a and b of the reducing valve; hence, piston 4- oi the 
latter is forced downwards the full length of its stroke, and 
assumes the position shown in view (e). In this position, the 
passage through ports a and b is small, and air discharges quite 
slowly from the cylinder. As the pressure in the cylinder, and 
consequently above piston 4-, gradually decreases, due to the 
discharge through ports a and b, the regulating spring gradually 
raises the piston and slide valve, and, as the slide valve is raised, 
the opening through ports a and b gradually increases; conse- 
quently, the discharge from the cylinder increases accordingly 
until the brake-cylinder pressure is reduced to a safe amount 
(60 pounds), when the reducing valve assumes its normal 
position, covering the opening a so that no more air can escape 
from the brake cylinder. 

IMPROVED AUTOMATIC REDUCING VALVE. 

28. The latest form of the high-speed automatic reducing 
valve is shown in Fig. 10. This is an improvement on the valve 
just described, the changes, however, not being very great. 
In the old-style valve, Fig. 9, it will be noticed that the piston 
4, when in its normal position, is intended to make an air-tight 
joint with the bushing at e, the piston and bushing being 



24 



THE AIR BRAKE. 



§4 



beveled for that purpose. In the new valve, the piston 4- 
includes a leather washer e, which forms an air-tight joint with 
the projection on the bushing. Also, the stem 6 has been 
shortened, and the guide 12 of the old valve is replaced in this 
valve by the spring abutment 22. The operation of this valve 
is exactly the same as that of the old-style valve. 



SAFETY VALVE. 

29. In cases where a car equipped with an automatic brake 
must be used in connection with high-speed brakes, and there 
is not sufficient time in which to equip it 
with a regular automatic reducing valve, a 
small safety valve is screwed into the oil 
hole in the brake-cylinder head and used as 
a substitute during the trip. A sectional 
view of this safety valve is shown in 
Fig. 11. It consists simply of the valve 
body 2, the valve 3, regulating spring 4, 
adjusting nut S, and lock cap 6. The end 
X is screwed into the oil hole in the cylinder 
head, and, consequently, that portion of the 
valve marked a is always subjected to brake- 
cylinder pressure. Ports y, y connect the 
chamber above valve 3 with the atmos- 
phere. 

The spring 4. is adjusted by means of the 
nut 5 until it resists from 50 to 60 pounds 
pressure per square inch on the valve 3. 
In adjusting either the safety valve or the 
automatic reducing valve, a gauge is 
attached to the brake cylinder, and the 
tension of the regulating spring is then 
adjusted until the gauge shows that the 
valve just retains the proper brake-cylinder 
pressure. 

The operation of the safety valve is as follows: As is the 
case with the automatic reducing valve, the safety valve remains 
in its normal position as long as the brake-cylinder pressure 




Fig. n. 




Fig. 12. 




Fig. 13. 



§4 THE AIR BRAKE. 25 



is less than that for which the valve is set to operate. If, 
however, the pressure in the brake cylinder exceeds that to 
which the spring 4 is adjusted, the valve 3 will be forced 
upwards, compressing the spring 4, and the brake-cylinder 
pressure will exhaust to the atmosphere through the valve 3 
and exhaust ports y, y until it is reduced to the pressure for 
which the valve is set; the spring 4 will then force valve 3 to 
its seat and the remaining pressure will be retained in the 
cylinder. As this is not a very reliable form of valve, it should 
only be employed temporarily in cases where the other form 
cannot be obtained. 

DUPLEX PUMP-GOVERNOR. 

30. A sectional view of the duplex pump-governor is 
shown in Fig. 12. By comparing Fig. 12 with Fig. 3 of Part 1, 
it will be seen that both the diaphragm bodies and the steam- 
valve body of the duplex governor are exactly the same as the 
corresponding parts of the ordinary governor (improved type). 
The only difference in the two governors is that the duplex 
governor is provided with the Siamese fitting S, and an extra 
diaphragm case. This governor is nothing more than a combi- 
nation of two diaphragm bodies with one steam valve body, 
and it operates in exactly the same way as the ordinary gover- 
nor, only one of the diaphragms acting at one time. The 
description of the improved governor, Art. 27, Part 1, applies 
to this governor also, and therefore no further description is 
necessary. It will be observed that in breaking away the 
steam-valve case in the illustration of this governor, a sufficient 
portion has been retained to allow the drip-pipe connection 36 
to be shown. Also, in breaking away the right-hand diaphragm 
case, part of the union fitting z has been left in. The parts 
of the valve are lettered and numbered the same as the corre- 
sponding parts of the valve shown in Fig. 3, Part 1. 



HIGH-SPEED BRAKE TRIPLE VALVE. 

31. Ordinary quick-action triple valves are used on the 
cars of a high-speed train. The plain triple used on the tender 
with the quick-action brake, however, is replaced in the 



26 



THE AIR BRAKE. 



4 



high-speed brake by a quick-action triple, while the plain 
triple used on the engine is replaced by another plain triple 
of special design. The engine triple, it will be remembered, 
operates both the driver and engine-truck brakes; hence, it is 
necessary to- use a triple designed especially for that purpose. 
Such a one is illustrated in Fig. 13. By comparing Fig. 13 
with Fig. 7 of Part 1, it will be seen that practically the only 
difference between this triple and the ordinary plain triple is in 
the size of the ports; the operation of the two valves is exactly 
the same. The corresponding parts of both triples are lettered 
and numbered similarly. 

SPECIAL CYLINDER HEAD. 

32. In order to use a quick- action triple on the tender- 
brake cylinder, it is necessary to replace the plain cylinder head 




Fig. li. 



with one like that shown in Fig. 14. The triple is secured 
to the part T in such a way that the port d of the triple, 
Fig. 9, Part 1, connects with the passage P in the cylinder head, 



THE AIR BRAKE. 



27 



while port Y connects (through the large central hole) with 
the space within T. The two tap bolts s, s serve as plugs for the 
two ports that lead to the space within T, and the pipe that 
leads from the auxiliary reservoir is screwed into either one or 
the other of the ports, as required. Air passes out from the 
triple and enters the cylinder head at P and passes on up 
through the interior of P' P" and so on into the brake 
cylinder. The automatic reducing valve is screwed into the 
cylinder head at r; r' is the cylinder oil plug. 



FEED-VALVE PIPE BRACKET. 

33. In order to use the duplex feed valve along with the 
F-6 brake valve, it is necessary to remove the original feed- 




Fig. 15. 



valve attachment and put a feed-valve pipe bracket in its 

place. A sectional view of this bracket, connected to the 
brake valve, is shown in Fig. 15. This figure represents 



28 THE AIR BRAKE. §4 



the same section of the F-6 brake valve as is given in view (e) 
of Fig. 16, Part 1. 

The two pipes a and 6, Fig. 8, that lead to the duplex feed- 
valve, screw into the pipe bracket 3 at a and b, Fig. 15. Thus, 
when the brake valve is in running position, air on its way to 
the train pipe flows through the passage /'/" and the pipe a, 
thence through whichever feed-valve happens to be cut in, 
and back through the pipe b and the passages i and I to 
the train pipe. 

OPERATING THE BRAKE. 



MAKING THE REDUCTIONS. 

34. The brake on a high-speed train is operated in 
precisely the same manner as the ordinary quick-action brake. 
A number of reductions are made in a service stop, as with the 
latter, and the brake will be set in full or at about its maximum 
pressure when a reduction of from 20 to 22 pounds is made in 
the train-pipe pressure, if the piston travel is adjusted to 
8 inches. In the high-speed system, the train pipe and auxilia- 
ries are charged to about 110 pounds pressure per square inch, 
so that the brake may be applied three times in full, and still 
have the same pressure for the fourth application as would be 
had for the second application of the quick-action brake. That 
is, if train-pipe pressure is reduced from 110 to 90 pounds, 
sufficient air will pass from the auxiliary reservoir to the brake 
cylinder to raise its pressure to about 50 pounds. If, now, the 
brake is released without recharging at all, and the train-pipe 
pressure is reduced from 90 to 70 pounds, the brake will again 
be set with a pressure of 50 pounds. A second release, and a 
reduction from 70 to 50 pounds, will set the brake for the third 
time with a 50- pound pressure, and the train pipe and auxiliary 
will stand equal at 50 pounds. With the quick-action brake, 
a 20-pound reduction from 70 pounds train pipe will apply the 
brake with 50 pounds pressure, and the train pipe and auxiliary 
will stand equal at 50 pounds also. In fact, with either brake, 
a 20-pound reduction from any pressure will apply the brake 
with a pressure of 50 pounds per square inch. 



§4 THE AIR BRAKE. 29 

With no leakage, a 22-pound reduction would set the brake 
with about 60 pounds pressure; hence, if a greater reduction is 
made, air will simply be wasted, since the reducing valve will not 
allow over 60 pounds pressure to remain in the brake cylinder. 

With a 30-pound service reduction and an 8-inch piston 
travel, the auxiliary and brake cylinder would equalize at 
about 80 pounds per square inch were the reducing valve 
inoperative; while, in an emergency application, they would 
equalize at about 85 pounds per square inch, on account of 
some air passing from the train pipe into the brake cylinder. 
In an emergency application, however, the reducing valve 
gradually reduces the brake-cylinder pressure from 85 pounds 
to 60 pounds. The effect that this extra pressure, when the 
brake is first applied, has on the braking power of a train, was 
brought out by a system of experiments conducted by the 
Pennsylvania Railroad. These experiments proved conclu- 
sively that, at a speed of 60 miles per hour, an emergency 
application of the high-speed brake will stop a train in 450 
feet less space than the ordinary quick-action brake. 



BRAKE TESTS. 

35. The tests referred to were made on October 1 and 2, 
1894, near Ship Road, Pennsylvania, on a descending grade of 
29 feet to the mile, the weather being fair and the rails dry. 
The train was made up of a locomotive and six Pennsylvania 
Railroad passenger cars, the total weight of the train being 
564,000 pounds. The train was fitted throughout with the 
high-speed brake equipment before the test began, and no 
alterations were made during the test. The brakes were con- 
verted from ordinary quick action at 70 pounds to high speed 
at a much higher pressure, and back again, by simply cutting 
in the proper pump governor and feed-valve, so that the same 
apparatus was used in all the tests. A correct speed recorder 
was used for measuring and recording the speed of the train, 
and the brakes were applied at a certain spot by means of a 
trip arrangement (connected to the train pipe) coming in 
contact with an obstruction that was fastened to one of the 



30 



THE AIR BRAKE. 



§4 



ties. This fixed the exact spot at which the brakes were 
applied, and enabled the length of the stop to be accurately 
measured. 

The tests on the first day were made at a speed as near 45 
miles per hour as possible, two tests being made with the ordi- 
nary quick-action automatic brake, and three with the high- 
speed brake cut in. The train-pipe pressure in the first two 
tests was 71 and 69 pounds, respectively, while in the last three 
tests it was 100, 104, and 100 pounds, respectively. 



RESULTS OF BRAKE TESTS. 

First Day. 



Train-Pipe 
Pressure. 
Pounds. 


Actual 

Speed in 

Miles per 

Hour. 


Length 

of Stop in 

Feet. 


Corresponding 

Length of Stop 

at 45 Miles 

per Hour. 


Average 

Length of Stop 

at 45 Miles 

per Hour. 


71 

69 

100 

104 

100 


47f 

451 
461 
46J 

47 


776 
697 
584 
610 
601 


6941 

683 j 
5671 
580 j- 

555 J 


688 
567 



Second Day. 



Train-Pipe 
Pressure. 
Pounds. 


Actual 

Speed in 

Miles per 

Hour. 


Length 

of Stop in 

Feet. 


Corresponding 

Length of Stop 

at 60 Miles 

per Hour. 


Average 

Length of Stop 

at 60 Miles 

per Hour. 


68 


60| 


1,697 


1,658] 




71 


61$ 


1,634 


1,558 j- 


1,622 


71 


58| 


1,584 


1,649 J 




100 


61J 


1,372 


1,319] 
1,299 1- 
1,269 J 




104 


61J 


1,361 


1,296 


105 


61$ 


1,330 




108 


58J 


1,125 


1,189 1 
1,155 J 


1,172 


109 


64i 


1,202 



§4 THE AIR BRAKE. 31 

On the second day, the tests were made at a speed as near 
60 miles per hour as possible, three tests being made with a 
train- pipe pressure of about 70 pounds, and five with a pressure 
of about 100 pounds. The observations taken during the tests 
are given in the preceding table. 

Explanation of Table. — Column 1 gives the train- pipe 
pressure used in each test; column 2 gives the actual speed 
of the train at the time the emergency application took place; 
column 3, the actual distance in feet the train traveled after the 
emergency application was made; column 4, the distance in 
feet the train would have traveled had it been running at the 
speed indicated (45 the first day, 60 the second), instead of at 
the actual speed as given in column 2; column 5 gives the 
averages of the distances marked with brackets in column 4. 

From column 5 it will be seen that, at a speed of 45 miles per 
hour, the high-speed brakes will stop a train in about 120 feet 
less space than the ordinary quick-action brake, while, at 60 
miles per hour, it will stop the train in about 450 or 326 feet 
less distance, depending on whether the train- line pressure used 
is greater or less than 105 pounds. 



CONTROL OF HEAVY FREIGHT TRAINS 
ON GRADES. 

36. The question of adequate brake power for trains 
on grades is an important one, especially when the operation of 
heavily loaded trains of large-capacity cars is considered. On 
medium grades, the quick-action brake has been found quite 
effective in both passenger and ordinary freight service, but, on 
very steep grades, it is extremely difficult and quite risky to 
attempt to control heavily loaded freight trains by means of the 
quick -action brake alone and without the aid of some special 
devices by means of which the braking power can be increased 
when necessary, to conform more nearly to the load. 

The Westinghouse Air Brake Company has invented a very 
simple and satisfactory method of improving the brake control 
of heavily loaded trains, which, while allowing the train to be 



32 THE AIR BRAKE. §4 

worked ordinarily at the standard train-line pressure, provides 
for a higher pressure when circumstances require it. The 
method necessitates no change in the ordinary quick-action 
car apparatus, all the changes necessary being made in the 
engine equipment. 



WESTI^GHOUSE SPECIAL APPARATUS. 



GENERAL ARRANGEMENT. 

37. This special brake apparatus and its arrangement 
on the engine and tender is shown in Fig. 16. It will be seen 
to differ from the ordinary equipment in that (1) the pump 
governor is replaced by a duplex governor; (2) the feed- valve 
attachment by a duplex feed-valve; and. (3) the engine triple 
valve by a special high-speed triple. The latter is necessary, since 
the engine-truck wheels, as well as the driving wheels, are fitted 
with brakes. Also, a safety valve, like that shown in Fig. 11, 
Art. 29, is connected to the engine and tender-brake cylinders 
to prevent the cylinder pressure from increasing above 50 
pounds per square inch, as it is not considered desirable to 
increase the pressure in either cylinder above that amount. 

The duplex feed- valve is exactly the same as that used in 
connection with the high-speed brake, and is attached to the 
brake valve in the same manner. One feed- valve is adjusted 
for 70 pounds, while the other is usually adjusted for 90 pounds. 

The duplex pump-governor, also, is the same as the one used 
with the high-speed brake, but it is piped differently, as will 
be seen by comparing Figs. 8 and 16. In the high-speed brake, 
both diaphragm cases of the governor are piped to the engi- 
neer's brake valve at R, while in Fig. 16, only the right-hand 
diaphragm case is piped to R, the other case being piped to a 
connection in the reversing cock, which leads to the chamber 
that communicates with the passage/" and chamber u of the 
fVed-valve, Fig. 17. Pipes c and a therefore connect with the 
same chamber in the reversing cock. By this arrangement of 
the piping, it is possible: (1) to regulate the train-pipe pres- 
sure to 70 pounds and the main-reservoir pressure to 90 as 



34 



THE AIR BRAKE. 



§4 



long as the brake valve is left in running position, and when 
the brake valve is moved to lap position, to pump up main- 
reservoir pressure to 110 pounds; or (2) to continuously regu- 
late the train-pipe pressure to 90 pounds and main-reservoir 
pressure to 110 pounds. 



OPERATION OF APPARATUS. 

38. Ordinary Running- Conditions. — Ordinarily, the 
handle of the pump-governor cut-out cock is turned parallel 
with the pipe, so that the 
left-hand side of the governor 
operates the air pump. The 
reversing-cock handle is also 
turned to the left, as shown in 
Fig. 16, so that the train-line 
pressure is regulated by the left- 
hand feed- valve. Now, suppose 
the brake valve to be in running 
position and the pump working; 
air from the main reservoir can 
pass through the brake valve and 
pipe a to chamber u of the left- 
hand feed-valve, Fig. 17, and 
thence through pipe c to the 
pump governor. As soon as 
main-reservoir pressure is raised 
to 90 pounds, the governor will 
stop the pump. Main-reservoir 
pressure will then be maintained 
at 90 and train-pipe pressure 
at 70 pounds, as long as the 
brake valve is carried in run- 
ning position. 

If a reduction in train-pipe 
pressure is made and the brake 
valve is then lapped, the supply valve 63 of the feed-valve will 
be forced from its seat by the regulating spring, and the air in 




§4 THE AIR BRAKE. 35 

pipe c will consequently be reduced to train-pipe pressure. 
Now, since no air can pass from the main reservoir through the 
brake valve into pipe c, the pressure in the pipe must remain 
less than 90 pounds as long as the brake valve is lapped; hence, 
the low-pressure side of the pump governor is cut out of service 
just as effectually as though the cut-out cock in pipe c had been 
closed. The pump, therefore, will operate until 110 pounds 
pressure is accumulated in the main reservoir, when it will be 
stopped by the high- pressure side of the pump governor. With 
110 pounds in the main reservoir with which to release the 
brakes, a quick release and prompt recharging of the auxilia- 
ries is assured. 

39. Descending Ijong Grades. — When the train is to 
descend a long grade, however, the cut-out cock in the pipe c is 
turned at right angles to the pipe, so as to cut the low-pressure 
side of the pump governor out of service, and the handle of the 
reversing cock is turned in the opposite direction to that shown 
in the figure, thus cutting into service the feed-valve that is 
adjusted to 90 pounds. Thus, when descending long grades, 
the main reservoir is charged to 110 and the train line to 
90 pounds. 

The brakes are operated in exactly the same manner as the 
quick-action brake, the only difference being that with the 
auxiliaries charged to 90 pounds, a full-service application of 
the brakes will result in a brake-cylinder pressure of about 
65 pounds per square inch instead of 50 pounds. 

When grades are exceptionally long and heavy, so that the 
driver brakes have to be held on hard for a considerable length 
of time, trouble is generally experienced with the driving-wheel 
tires heating, the friction between the brake shoe and the 
wheel generating heat that expands the tire. On such grades, 
therefore, the brake known as the water brake can be used 
to good advantage. 



36 THE AIR BRAKE. §4 



THE WATER BRAKE. 



PRINCIPLES INVOLVED. 



40. If the valve gear of a locomotive is reversed while 
the locomotive is running forwards with throttle closed, the 
engine cylinders will be converted into air compressors. As 
the piston moves either forwards or backwards, a vacuum is 
created in the cylinder behind it and hot gases from the smoke- 
box are drawn in to fill the vacuum. The gases in the cylinder 
ahead of the piston are compressed, and offer a resistance that 
acts to stop the movement of the piston, and thus the speed of 
the engine is retarded. 

With the valve gear in the reverse direction to which the 
engine is running, therefore, the engine cylinders act as brakes 
to retard the speed of the train. If the air drawn into the 
cylinders were cool and free from cinders, this method of 
braking would be simple and very efficient for use on engines 
on long down grades. As it is, however, cinders would be 
drawn into the cylinders and cause trouble; also, the gases 
in the smokebox are very hot, and, when drawn in, their 
temperature is still further increased by compression; hence, 
serious injury would result to the cylinders, valves, and valve 
seats, if this method of braking were used without some 
means of preventing the hot gases and cinders from entering 
the cylinders. 

The water brake (sometimes spoken of as the LeChatelier 
brake) overcomes the objections to this method of braking by 
introducing wet steam at a low pressure into the cylinders, 
thereby excluding the hot gases. Unfortunately, the term 
"water brake " is a misnomer when applied to the LeChatelier 
method of braking, and is very liable to create the impression 
that water is used in the cylinders, whereas, in reality, the 
braking is done by means of low-pressure wet steam. It is 
scarcely necessary to remark that water in the cylinders has 
too often been the cause of considerable trouble fc>r any one 
to voluntarily introduce it there. 



THE AIR BRAKE. 37 



CONSTRUCTION OF BRAKE. 

41. The -water brake was invented nearly fifty years ago 
by a prominent French engineer named LeChatelier, but it 
was not introduced in this country until years afterwards, 
being first used on the early mountain roads in the Rocky Moun- 
tains, a region where it has proved a very valuable auxiliary 
braking device. This brake is shown applied to an engine in 
Figs. 18 and 19, the former being a plan view of engine, and 
the latter a view taken at rear of cylinders. The brake appa- 
ratus consists of an ordinary globe valve a and sufficient piping 
bbb to connect the valve with the exhaust passages in the cylin- 
der saddle at c, c. The globe valve is set in the boiler head, on 
a level with the crown sheet and at a point where it will be 
within easy reach of the engineer. The pipe used in con- 
nection with the globe valve is either a f-inch or a J- inch pipe, 
depending on the size of the engine cylinders. It divides into 
two branches at the cylinder saddle, each branch leading to, 
and opening into, one of the exhaust passages, as shown. 



OPERATION OF PARTS. 

42. As previously stated, the duty of the water brake is 
to supply low-pressure steam to the cylinders when the engine 
is running reversed, so that, by acting as compressors, the 
cylinders can be used as an auxiliary braking device without 
being injured by hot gases and cinders from the smokebox. 
It is well known that water will boil at 212° F. if in the open 
air; if subjected to a boiler pressure of, say, 180 pounds gauge, 
however, it will not boil until its temperature has been raised 
to about 380° F. If, now, some of the water in the boiler 
is allowed to escape into a pipe or vessel connected with the 
atmosphere, its temperature will be far greater than 212° F. ; 
hence, it will boil and be converted into steam. The tem- 
perature of this steam, however, falling considerably during 
the conversion, the pressure exerted by it will be reduced 
accordingly. 



§4 



THE AIR BRAKE. 



39 



The valve and piping of the water brake simply provides the 
engineer with a convenient means of introducing water from 
the boiler into the exhaust passages in the cylinder saddle, 
where it is immediately converted into steam for use in the 
cylinders. By introducing the water into the exhaust passages, 




Fig. 19. 
a vacuum is prevented from forming therein; hence, there is no 
tendency for the hot gases in the smokebox to be drawn into 
the cylinders. 

It thus will be seen that the operation of this brake depends 
on the excess temperature of the water in the boiler over that 
required to boil water under atmospheric pressure; if the water 
in the boiler were at a temperature less than 212° F., it would 
not be converted into steam when discharged into the exhaust 
passages, and the result would probably be a broken cylinder 
head. 



OPERATING THE BRAKE. 

43. The water brake should always be operated in a 
certain regular order, which is as follows: First, be sure 
that all the cylinder cocks are open and that the throttle valve 
is shut; next, open the water valve (i. e., the globe valve a) 
about one-quarter turn; then immediately place the reverse 



40 THE AIR BRAKE. §4 



lever of the engine one or two notches back of the center and 
note the color of the steam issuing from the cylinder cocks. If 
dense white in color, the water valve is open sufficiently, but if 
the steam has a bluish color at the cylinder cock, which grad- 
ually changes to grayish white as its distance from the cock 
increases, the water valve should be opened a little wider until 
the steam has a dense white appearance from the moment it 
leaves the cylinder cocks. If the engine throws water from 
the stack, the valve is opened too wide and should be closed 
sufficiently to stop the trouble. 

The amount of braking power exerted by the water brake 
depends on the position of the reverse lever. When it is in 
the first notch from the center, it exerts the least braking power, 
and the braking power is increased as the lever is moved towards 
the corner notch. The retardation of speed should therefore 
be regulated by placing the reverse lever in the notch required, 
and the water valve should not be changed after once being 
adjusted. 

The water brake can be used when the engine is running 
either forward or backward, by simply placing the reverse 
lever so as to convert the cylinders into air compressors, 
observing the same rules of operation, regardless of the 
direction of running. 

When it is desired to shut off the water brake, first close the 
water valve a and then slowly move the reverse lever towards 
the center, to avoid throwing water from the stack. 

The water brake, it must be remembered, acts to stop the 
rotation of the drivers, so that if the air driver brake is used 
in conjunction with it, the braking force acting on- the drivers 
will be too great, and they will be skidded. The water 
brake is simply an auxiliary braking device and should be 
used intelligently. It is most effective on a steady motion of 
from 3 to 12 miles per hour, is less effective at speeds greater 
than 12 miles per hour, and it should not be used at a greater 
speed than 18 miles per hour. 

In double-heading on a grade, the engineer not operating the 
air brake assists in retarding the speed of the train by using the 
water brake to whatever extent advisable. 



§4 THE AIR BRAKE. 41 



THE SWEENEY AIR COMPRESSOR. 

PRINCIPLES OF WORKING. 

44. The Sweeney air compressor, or the "Sweeney," as it is 
commonly called, is an air-compressing device that is used quite 
extensively on Western roads where the grades are heavy. It is 
not intended to replace the ordinary air pump, but rather to act 
as an auxiliary compressing device to help out the pump. In 
case the pump becomes disabled, however, it may be made to 
supply the entire amount of air necessary to bring the train 
safely down the grade. 

CONSTRUCTION OF COMPRESSOR. 

45. Two views of the Sweeney, applied to an engine, are 
given in Fig. 20 (a) and (6). It will be seen that a lj-inch 
pipe is tapped into the top of the steam chest at a, and thence 
leads to the main reservoir. A stop-cock c is placed in the pipe 
so as to control the passage through it. This stop-cock can be 
opened and closed from the engine cab by means of the rod e, 
which is connected to the lever b of the stop-cock. Pushing 
the handle forwards opens the cock, while pulling it backwards 
closes it. Also, a check- valve v is placed in the pipe, close to 
the main reservoir. The object of this valve is to prevent 
pressure from flowing from the main reservoir back through the 
pipe to the steam chest. A safety valve d is also provided, 
which prevents the main reservoir from being overcharged, 
since it will open and allow the air to discharge from the 
cylinders to the atmosphere when main- reservoir pressure is 
raised to the pressure for which the safety valve is adjusted. 



OPERATING THE COMPRESSOR. 

46. To operate the Sweeney, the throttle must, of course, 
be closed, and the engine running. The cylinder cocks should 
first be left open while the drivers make two or three revo- 
lutions, so as to get rid of any water there may be in the 



§4 THE AIR BRAKE. 43 



cylinders. The engineer's brake valve should then be placed 
on lap, the stop-cock c opened, and the engine reverse lever 
placed several inches back of the center notch, assuming the 
engine to be running forwards. By reversing the valve gear 
while the engine is running, the cylinders are converted into air 
compressors, and air is compressed and forced into the steam 
chest and thence through the 1 J- inch pipe to the main reservoir. 
As the capacity of the steam cylinders is large compared with 
that of the air-pump cylinder, the main reservoir is charged in 
a very short time by this method. The reverse lever must be 
left back of the center notch at least 15 seconds after the gauge 
indicates standard pressure. 

To throw the Sweeney out of service, place the reverse lever 
in the forward motion and close the stop-cock c; care must 
always be taken to see that the stop-cock is closed before steam 
is used, since, if it is left open, the air-brake system will be 
charged with steam when the engine throttle is opened, and 
trouble will surely result. 



A SERIES OF QUESTIONS 

Relating to the Subjects 
Treated of in This Volume. 



It will be noticed that the questions contained in the follow- 
ing pages are divided into sections corresponding to the sections 
of the text of the preceding pages, so that each section has a 
headline that is the same as the headline of the section to 
which the questions refer. No attempt should be made to 
answer any of the questions until the corresponding part of the 
text has been carefully studied. 



The Air Brake 



(PART 1.) 



Note. — In describing the construction or working of the various 
brake details, when answering the following questions, we should prefer 
that the student refer to the various parts by their proper names instead 
of using the reference letters and numerals given in the text; all his 
replies, moreover, should be in his own language, and not be merely 
copies from the book. In dealing with some of the questions, he may 
profitably experiment with the brake apparatus on his engine, as this 
will help to fix its various operations in his mind. Still, all the ques- 
tions can be satisfactorily reasoned out and answered without such aid, 
if the text has been carefully studied. 

(1) Explain how the air end of the 8-inch air pump works. 

(2) (a) How great a train-pipe reduction (from 70 pounds) 
is necessary to get a full-service application of the brakes? 
(6) Would a still greater reduction set the brakes any harder, 
and would it be advisable to do so ? Give reasons for your 
answer, (c) When a brake is set with a full-service applica- 
tion, how much pressure is there in the auxiliary reservoir, and 
how much in the brake cylinder? 

(3) (a) How would you operate the brake valve to make 
an emergency application of the brakes? (6) Explain the 
working of the valve in an emergency application. 

(4) Speaking generally, (a) what will cause the brakes to 
set? (b) what will cause the brakes to release ? 

(5) Explain how the steam end of the 8-inch air pump works. 

(6) Can an emergency application of the brakes be obtained 

by making a gradual heavy reduction of train-pipe pressure? 

Explain. 

§i 



THE AIR BRAKE. §1 



(7) In what position would you carry the brake valve 
between the reductions in a service application of the brakes, 
and why ? 

(8) (a) What is meant by excess pressure, where is it carried, 
and why is it necessary? (6) How is excess pressure main- 
tained when an F-6 brake valve is used ? 

(9) Why were the ports c and / provided in the improved 
pump governor? 

(10) (a) Does a plain triple set the brake harder in an 
emergency than in a service application? Explain in full. 
(6) Does a quick-action triple, and if so, why? 

(11) (a) How would you make a service reduction with 
either style of brake valve? (b) In making such a reduction, 
do you draw air direct from the train pipe, and if not, from 
what place is it drawn? (c) Explain how the tr. in-pipe 
exhaust valve E works. 

(12) (a) Why is the small equalizing reservoir provided, 
and how is it connected to chamber D of the brake valve? 
(6) If the pipe to this reservoir became completely stopped up, 
how would it affect the working of the brake? 

(13) By what pressure is the pump governor operated when 
used in connection with (a) the D-8 brake valve, and (6) the 
F-6 brake valve? (c) Explain how the improved pump- 
governor works. 

(14) Where does all the air come from that enters the 
brake cylinder during an emergency application, with (a) the 
plain triple, and (b) the quick-action triple? 

(15) (a) In what position would you place the brake valve 
to release the brakes? (b) Trace the flow of air through the 
brake valve (D-8 or F-6) in this position. 

(16) What is the engineer's warning port, and why is the 
F-6 brake valve provided with one? 



§1 THE AIR BRAKE. 



(17) What pressure does (a) the red hand, and (6) the 
black hand, of the duplex air gauge indicate? 

(18) How great a train-pipe reduction is necessary to get a 
full emergency application of the brakes (a) with plain triples, 

with quick-action triples? Explain fully. 



an 



ii emergency application oi tne DraKes {a) witn ; 
d (6) with quick-action triples? Explain fully. 

(19) (a) State the duty of the ports e,f, g, h, k, and I, and 
also of cavity b, in a rotary-valve seat. (6) What is the duty 
of port j in the rotary valve? 

(20) If, after releasing the brakes with a D-8 brake valve, 
the valve is moved to lap position while train-pipe pressure is 
only 65 pounds, (a) how will the two gauge hands move as 
the pump raises the pressure in the main reservoir? (6) When 
the pump stops, what pressure will there be in the main reser- 
voir, train pipe, and chamber D? Also answer questions (a) 
and (6), assuming that an F-6 brake valve is used instead of a 
D-8 valve. Explain your answers fully. 

(21) (a) Where is the main reservoir usually located, and 
how much pressure does it usually carry? (6) Explain why a 
larger main reservoir is necessary in freight than in passenger 
service, (c) -Why should water not be allowed to accumulate 
in the main reservoir, and how often should the reservoir 
be drained? 

(22) Explain how the plain triple works, and trace the flow 
of air through it, (a) in releasing the brakes; (6) in making 
two reductions during a service application; and (c) in an 
emergency application. 

(23) What is the duty of the retaining valve, and how 
does it work? 

(24) Assume that, in releasing the brakes with a D-8 brake 
valve, main-reservoir pressure equalizes with the train pipe at 
65 pounds pressure; after which, the brake valve is moved to 
running position, (a) Which gauge hand will move first when 
the governor starts the pump, and how far will it go before the 



THE AIR BRAKE. § 1 



other hand moves? Give reasons. (6) What pressure will 
there be in the main reservoir, train pipe, and chamber D, when 
the governor stops the pump? Also answer questions (a) and 
(5), assuming that an F-6 brake valve is used instead of a D-8. 
Explain your answers fully. 

(25) Name the essential parts of the automatic brake, and 
state what each part is for. 

(26) (a) What are the three duties of a triple valve? 
(b) What is the duty of the graduating valve in a triple, and 
how does it work? (c) What is the duty of the triple piston, 
and of the graduating stem and spring ? 

(27) (a) Why are brake cylinders provided with a leakage 
groove similar to that marked a in Fig. 10? (6) What is the 
duty of the bleed cock 17, and how is it used? (c) What 
returns the brake-cylinder piston to release position when the 
brake is released? 

(28) If a D-8 brake valve is allowed to remain in release 
position after releasing the brakes, (a) how much pressure will 
there be in the train pipe, in chamber D, and in the main 
reservoir, when the governor stops the pump? (6) How much 
would there be in the above places if the D-8 brake valve were 
replaced by an F-6 valve ? Explain your answers fully. 

(29) Why was the plain automatic brake replaced by the 
quick-action automatic brake? 

(30) Explain clearly how the air end of the 9J-inch air 
pump works. 

(31) Explain how the quick-action triple works, and trace 
the flow of air through it (a) in a service application, and (6) in 
an emergency application. 

(32) (a) What is the duty of the feed- valve attachment of 
the F-6 brake valve? (6) Explain how it works, and how it 
can be adjusted to regulate as desired. 



§ 1 THE AIR BRAKE. 



(33) When the plain automatic brake was adopted, what 
addition to the straight-air car equipment was necessary in 
order to convert it into an automatic equipment? 

(34) Explain briefly how the steam end of the 9J-inch 
air pump works. 

(35) (a) What constitutes the emergency part of the quick- 
action triple? (6) What is the duty of the rubber-seated 
emergency valve? (c) What is the duty of the check-valve 
15, and what causes it to unseat and seat again during an 
emergency application? 

(36) How does the excess-pressure valve in the D-8 brake 
valve maintain a difference of 20 pounds between the train 
pipe and the main reservoir when the brake valve is in 
running position ? 

(37) What defects in the straight-air brake system caused 
it to be abandoned ? 

(38) In the 9J-inch air pump, what is the duty of slide 

valve 83, main valve 76, and reversing valve 721 

• 

(39) Can the brake on any car be cut out without inter- 
fering with the rest of the brakes on the train, and if so, how ? 

(40) When and why should the brake valve be carried 
in running position? 



The Air Brake. 

(PART 2.) 



(1) How would you test for worn steam-piston packing 
rings ? 

(2) If an 8-inch pump stops, where would you look for 
the cause? 

(3) What will be the effect of a badly worn packing ring 
in a plain triple? 

(4) How would you test for a leaky rotary valve? 

(5) What effect will a leak at the pin valve of a pump 
governor have? • 

(6) How would you test for a leaky receiving valve in an 
8- inch air pump? 

(7) If an air pump stops, how would you proceed to 
start it? 

(8) Name the defects that will cause a blow at the exhaust 
port of a plain triple. 

(9) Explain fully how to remove and clean an excess-pres- 
sure valve. 

(10) What will be the effect if the relief port c in an 
improved governor is stopped up? 

(11) How would you determine whether a receiving valve 
in a 9^-inch pump is leaking? 

22 



THE AIR BRAKE. 



(12) How large is the feed groove in a triple valve made? 

(13) . Explain in detail how a triple valve should be cleaned. 

(14) If for any reason an excessive pressure is pumped up 
in the main reservoir, what precautions should be observed 
when releasing brakes? 

(15) What will be the effect if the governor drip pipe 
becomes frozen or stopped up? 

(16) If an auxiliary charges too slowly, to what would 
you attribute the cause? 

(17) What will be the effect of a leaky discharge valve, 
and how can you tell whether one is leaking or not? 

(18) State the causes of trouble in the freight equipment, 
and give the effects of each cause. 

(19) In what two positions of a D-8 brake valve will the 
black gauge hand indicate main-reservoir pressure? 

(20) What effect will a "buckled" diaphragm in an old- 
style governor have? 

(21) If the air valves in an air pump have too much lift, 
what will be the result? 

(22) What effect will leaks in the train pipe have on the 
triple valves? 

(23) Explain how the freight equipment should be cleaned 
and oiled. 

(24) Why, when the train pipe is short, does a blow some- 
times occur at the train-pipe exhaust port on releasing the 
brakes ? 

(25) If the governor becomes inoperative and cannot be 
repaired during the run, how would you cut it out of service so 
that the pump can be operated by hand ? 



§2 THE AIR BRAKE. 



(26) How can you tell whether a receiving air-valve is 
stuck shut? 

(27) What will be the effect if an auxiliary reservoir or 
its connections leak? 

(28) How would you test a retaining valve? 

(29) How would you test whether the pump governor is 
properly adjusted? 

(30) If the governor has to be cut out of service, can the 
pump be governed, and if so, how ? 

(31) How can you tell whether a discharge air- valve is 
stuck shut? 

(32) What will be the effect if the strainer in a triple 
valve is parti y stopped up? 

(33) State the advantages to be gained by the use of 
retainers. 

(34) How can you test whether the feed-valve attachment 
needs regulating? 

(35) What precautions should be observed in packing an 
air pump? 

(36) Where would you look for a leak from an auxiliary 
reservoir ? 

(37) State the causes of pounding in an 8-inch pump. 

(38) Give the causes of trouble in the retaining valve; 
also their effects. 

(39) If no excess pressure can be maintained with an 
F-6 brake valve, where would you look for the cause? 

(40) What kind of oil, and how much of it, should be 
used in the air cylinder of a pump? 



THE AIR BRAKE. §2 



(41) State the causes of pounding in a 9|-inch pump. 

(42) How will a leaky graduating valve affect the operation 
of the brake? 

(43) If a retainer is broken from its pipe, will the brake 
apply and release properly ? Explain clearly. 

(44) How can you tell whether the gasket 32 of an F-6 
brake valve is leaking? 

(45) How should the oil be introduced into the air cylinder 
of a pump? 

(46) What should be the lift of the air valves in both the 
8-inch and the 9^-incb pumps, and what effect will too little 
lift have? 

(47) Does a defective graduating spring in a triple valve 
have the same effect when the train pipe is long as when it is 
short? Explain fully. 

(48) If a retainer is broken from its pipe, should the pipe 
be plugged? Give reasons. 

(49) Explain clearly how you would remove and clean the 
supply valve 63 of the feed-valve attachment. 

(50) Should oil ever be introduced into an air pump 
through the air inlets? Give reasons. 

(51) State the causes that will produce a blow in a 9J-inch 
pump; also, whether the blow will be continuous, and if not, 
whether it will occur on the up or on the down stroke. 

(52) Explain how a " sticky " triple will cause trouble. 

(53) How can you test — by means of the brake valve — 
whether the air gauge is correct? 

(54) What would you do in the event of the feed-valve case 
gasket 27 allowing air to leak between the ports /'/" aR d i? 



THE AIR BRAKE. 



(55) Should kerosene or coal oil ever be used in a hot 
pump? Give reasons. 

(56) State the causes of a blow in the 8-inch pump. 
Explain fully. 

(57) If the pin that connects the graduating valve 7 to the 
triple-piston stem is broken, what effect will it have? 

(58) If the excess-pressure valve spring were too weak, how 
would the fact be indicated, and what would be the remedy? 

(59) If a continuous blow occurs at the train-pipe exhaust, 
to what would you attribute it, and how would you proceed to 
stop it? 

(60) If the air passages in an air pump becomes gummed 
up, how may they be cleaned out? 

(61) If the 9J-inch pump should stop, where would you 
look for the cause? 

(62) Does the handle of the brake valve have to be left in 
service position any longer when the train pipe is long than 
when it is short, to make a 5-pound train-pipe reduction? 

(63) What would be the effect and remedy if the excess- 
pressure spring were too stiff? 

(64) What would be the effect of a leak in the equalizing 
reservoir or its connections? 

(65) Explain clearly how an air pump should be started, 
and at what speed it should be run. 

(66) If a 9J-inch pump stops, how can you test whether 
the pump governor is responsible for the trouble? 

(67) If a blow occurs at the exhaust port of a quick-action 
triple, where would you look for the cause? 

(68) What would you do if the excess-pressure spring 
should break? 



THE AIR BRAKE. §2 



(69) In case of a bad leak in the equalizing reservoir or its 
connections, such that the brake system is rendered inoperative, 
what would you do ? 

(70) Give your ideas in regard to the lubrication of the air- 
pump steam cylinder. 

(71) How can you determine whether the pump governor 
is responsible for the 8-inch air pump stopping? 

(72) What difference is there in the blow that occurs at 
the triple exhaust, due to a leaky slide valve or to a leaky 
emergency valve ? 

(73) If a D-8 brake valve fails to maintain excess pressure, 
to what might it be due ? 

(74) If the brakes cannot be applied from service position, 
what precautions should be observed in making service stops 
from emergency position ? 

(75) Give the causes of an air pump overheating. 



The Air Brake. 

(PART 3.) 



(1) How should a terminal test of a train be made? 
Explain fully. 

(2) (a) If a blow occurs at the exhaust port of a triple or 
of a pressure retainer, to what may it be due? (b) In the 
event of such a blow, would you plug the exhaust port? Give 
reasons. ¥ 

(3) How should a service stop be made with a passenger 
train ? 

(4) How would you make a water- tank or coal-chute stop 
with (a) a part-air freight train? (6) an all-air freight train? 

(5) If you were to pick up several cars, which probably 
were uncharged, how would you proceed so as to save time? 

(6) Explain when and how you would use sand on 
the rails. 

(7) Within what limits should the piston travel be main- 
tained on (a) a passenger car? (b) a freight car? (c) the 
tender? and (cZ) the driver brakes? 

(8) Where would you look for the cause if your driver 
brake (a) failed to apply? (b) failed to release? (c) released 
ini mediately after it had set? 

(9) Where are leaks liable to occur in (a) the train pipe 
and branch pipes? (6) the hose and couplings? (c) the 
auxiliary reservoir? and (<2) the brake cylinder? 

§3 



THE AIR BRAKE. § 3 



(10) In making a service stop, how many reductions should 
be made, and how great should each reduction be? 

(11) If it were necessary to use the hand-brakes in con- 
junction with the air brakes, would you use those at the rear 
end of the train? Give your reasons. 

(12) How would you proceed to set out a car at a way 

station ? 

(13) How would you locate a triple that set its brake 
u quick action " when a service reduction was made? 

(14) Suppose that in the same train there are two cars 
having brake-piston travels of 4 and 10 inches, respectively. 
(a) At what pressures would they equalize ? (6) Which would 
equalize first? (c) Which would release first? 

(15) How should a part- air train be made up? 

(16) How can you determine the condition of the triple 
piston packing-ring without taking the triple down ? Explain 
fully. 

(17) (a) How can the condition of the brakes be ascer- 
tained by means of the temperature of the car wheels ? 
(6) How can defects be located by means of the tempera- 
ture test ? 

(18) Explain fully how a service stop should be made with 
a part- air train. 

(19) How would you handle a train on a long down grade? 

(20) Suppose the brake-piston travel on three cars to be 
4, 8, and 10 inches, respectively; what will be the pressure in 
the three brake cylinders if a train-line reduction of 16 pounds 
is made? 

(21) What is the greatest allowable pressure on the brake 
shoes of (a) passenger cars? (b) freight cars? (c) tenders? 
(d) driving wheels? 



§3 THE AIR BRAKE. 3 

(22) How would you stop a train in an emergency? 
Explain fully. 

(23) Does the length of the train pipe have any effect on 
the way the train " handles," and if so, what? 

(24) What should the engineer do in case the brakes apply 
suddenly, from no apparent cause? 

(25) If, in making a terminal test, a brake was found that 
would not release, (a) where would you look for the cause? 
and (6) what would you do? 

(26) Why is it bad practice to make more than two appli- 
cations in stopping a train ? 

(27) If the driver brakes are applied, should the engine be 
reversed to help stop the train in an emergency? Give reasons 
for your answer. 

(28) What course would you pursue in the event of (a) an 
all-air train breaking in two? (6) a part-air train breaking 
in two ? 

(29) How and when should a running test of the brakes 
be made? 

(30) When double-heading, what are the duties (a) of the 
leading engineer? (b) of the following engineer? 

(31) (a) What would you do in case a hose burst? (6) 
How can the engineer help to locate a burst hose? 

(32) How can the braking power of a cam driver- brake be 
determined? 

(33) If a stop is to be made with two applications of the 
brake, what would be the effect of overcharging the train pipe 
when releasing after the first application? 

(34) Explain how you would cut a car out. 

(35) How should a stop on a grade be made with a pas- 
senger train? 



THE AIR BRAKE. §3 



(36) Explain how you would cut a car brake out of service. 

(37) If, in making a terminal test, a brake is found that 
will not stay on, (a) where would you look for the cause? 
and (6) what would you do? 

(38) Explain how "slack" affects the smooth handling 
of a train. 

(39) When and how should the conductor's valve be used? 

(40) How would you "bleed off" a brake? 

(41) Explain fully how to adjust the brakes (a) on a car; 
(b) on a cam driver-brake; (c) on an American equalized 
driver brake. 

(42) What causes wheels to slide? 

(43) What precautions should be observed in stopping and 
starting a long all-air freight train? 

(44) If, in making a terminal test, a brake is found that 
will not apply, what would you do? 

(45) If the brake-piston travel is not uniform throughout 
the train, being, say, 4 inches on some cars and 10 inches on 
others, will the smooth handling of the train be thereby 
interfered with ? Explain. 

(46) How would you measure the piston travel on a 
freight car? 



The Air Brake 

(PART 4.) 



(1) Explain the operation of the signal valve. 

(2) (a) How much pressure must be carried with the 
new style of signal reducing valve ? (6) How much with the 
old style? 

(3) (a) How much pressure is carried in the train pipe of 
the high-speed brake? (6) What amount of excess pressure 
is there in the main reservoir? 

(4) A train now fitted with the ordinary quick-action brake 
is to be equipped with the Westinghouse special apparatus for 
controlling heavy trains on grades; what changes must be made 
in the existing equipment? 

(5) Why is the Sweeney air compressor applied to engines 
working in mountainous districts? 

(6) On what class of trains is the high-speed brake chiefly 
used, and why is it necessary on these trains more than 
on others ? 

(7) If, on pulling the signal cord on a car, you obtained a 
very long blast from the whistle, where would you suspect the 
trouble to lie? 

(8) (a) In using the Sweeney compressor, how long should 
the reverse lever be kept back of the center notch ? (b) Should 

H 



THE AIR BRAKE. §4 



the engineer ever work steam when using this device ? (c) Do 
you think it is advisable for the engineer to test this apparatus 
after leaving a terminal ? 

(9) If the signal whistle gives only a weak blast when the 
cord is pulled, to what would you attribute the trouble? 

(10) Explain the operation of the high-speed automatic 
reducing valve. 

(11) (a) Explain the construction of the Sweeney com- 
pressor. (6) How is it operated? 

(12) With the high-speed brake, about 85 pounds is 
obtained in the brake cylinder on the brake first setting; as the 
speed slows down, this pressure gradually drops to 60 pounds. 
How is this accomplished ? 

(13) (a) How and when should the signal apparatus on 
the engine be tested? (6) Is it reliable to make a test with 
the stop-cock on the rear of the tender or front of the engine? 
Explain. 

(14) With the high-speed brake, 110 pounds pressure is 
usually carried in the train pipe. If we made an emergency 
application, at what pressure would the auxiliarj^ and the brake 
cylinder equalize? 

(15) What is the duty of the safety valve that is connected 
to the engine and tender brake when the Westinghouse special 
apparatus is used ? 

(16) Explain the operation of the improved air-signal 
reducing valve. 

(17) If the whistle blows every time the brakes are 
released, where would you look for the cause? 

(18) (a) If an engine equipped with the high-speed brake 
were to be coupled to a train likewise so equipped, in what 



§4 THE ATR BRAKE. 



position would you place the handle of the feed- valve reversing 
cock and of the pump- governor cut-out cock, and why would 
you so place them? (6) If the engine were to be coupled to a 
train having ordinary quick-action brakes, in what position 
would you place the handles? Give reasons for you answers. 

(19) Explain the principle of the water brake. 

(20) (a) How can the air signal be operated most success- 
fully from the cars? Explain. (/;) What time should elapse 
between two successive discharges from the car discharge 
valve ? Explain. 

(21) When, only, should the small safety valve shown at A 
in Fig. 8, Part 4, be used in high-speed service? 

(22) (a) Explain how to -apply the water brake. (6) At 
what speeds should it be used? (c) Should the driver brakes 
and the water brake be used together; and if not, why ? 
(ri) Explain how to proceed when it is desired to "shut off" 
the water brake. 

(23) (a) What defect may cause the signal whistle to give 
two blasts when the cord is pulled? (6) How can this defect 
be remedied? 

(24) What changes are necessary in the apparatus of the 
ordinary quick-action brake to convert it into the high-speed 
brake? 

(25) Explain how the Westinghouse special apparatus for 
the control of heavily loaded trains is used (a) on grades, (6) 
on a level section. 

(26) In applying the water brake, what would probably 
happen if the engineer opened the water valve too wide? 

(27) If the signal pipe fails to charge, where would you 
look for the cause? 



THE AIR BRAKE. 



(28) If a signal can be transmitted from the forward cars 
of a long train, but not from the rear cars, where would you 
look for the cause of the trouble ? 

(29) Explain how you would operate the brakes of a train 
equipped with the high-speed brake. 

(30) If the signal whistle does not blow when the signal 
cord is pulled, where would you look for the cause? 

(31) Explain how to transmit signals by means of the air- 
signaling system. 

(32) What are the advantages of the high-speed brake over 
the ordinary quick-action brake ? 



INDEX 



A. 

Sec. Page. 

Adjusting brakes 3 40 

Air brake, Automatic 1 3 

General equipment of 1 1 

Historical account of 1 1 

" hose 1 43 

" The straight 1 1 

" cylinder of 8-inch pump 1 19 

" 9Hnch pump 1 26 

Oiling 2 5 

" gauge 1 5 

'•' Duplex 1 10 

" passages stopped up 2 11 

'• piston nuts loose 2 19 

'• pump 1 4 

" Testing 3 5 

" The 8-inch 1 16 

" The9Hnch 1 21 

" signaling system 4 1 

Defects in 4 11 

Testing 4 15 

" valve stuck shut 2 11 

" valves, Lift of 2 7 

All-air train 3 4 

" " freight train 3 24 

Apparatus for working heavy 

freight trains on grades 4 32 

Application, Emergency 1 33 

Applications, Number of 3 21 

Applying the brake 1 31 

Automatic air brake, General Ar- 
rangement of 1 4 

Auxiliary reservoir 1 7 

1 41 

Charging 1 31 

" too 

slowly 2 20 

leaks, Effect of 2 22 

B. 

Bleed cock 1 41 

Bleeding brakes off 3 29 

Blow at exhaust (plain triple) 2 29 

" " " (quick-action 

triple) 2 23 

Brake, Applying 1 31 

Cutting out 3 14 

cylinder 1 7 

1 41 



Sec. Page. 



Brake cylinder, Cleaning 

" Force exerted in 

Oiling 

packing leather 

" pressure :■: 

fails to apply 

" " release 

gear 

High-speed 

Outside equalized driver 

piston sleeve split 

power 

" Calculation of 

shoe pressure 

tests 

valve position while run- 
ning 

positions, The various 

reservoir..... 

Testing 

Water 

will not stay on 

Brakes, Adjusting 

Bleeding off 

Holding on 

Releasing 

stuck on 

Branch pipes, Leaks in 

Breaking-in-t wo of train 

Burst hose 

" " To locate 



C. 

Calculating the power of cam dri- 
ver-brake 3 55 

Calculating the power of Hodge 

brake gear 3 52 

Calculating the power of outside 

equalized brake gear 3 57 

Calculating the* power of Stevens 

brake gear 3 55 

Cam driver-brake 3 42 

Car, Braking power required for 3 59 

" Cutting out 3 15 

" discharge valve (signal) 4 8 

" equipments 1 40 

" Picking up 3 28 

" Setting out 3 27 



vni 



INDEX. 



Sec. Page. 

Care of engineer's valves 2 46 

" " triples 2 30 

Chamber D 1 49 

" " Purpose of 1 49 

Charging auxiliary reservoir 1 31 

" Time 
required 

for 2 20 

Cleaning the brake cylinder 2 33 

" " feed-valve attachment 2 47 

" pump (inside) 2 6 

" triples 2 33 

Clearance in pump 2 13 

Coal-chute stops 3 23 

Comparison of plain and quick- 
action triples 1 39 

Compound lever 3 50 

" Law of 3 51 

Conductor's valve 1 7 

" Use of 3 34 

Coupling hook 1 44 

Couplings, Frozen 3 14 

Cut-out cock 1 6 

Cutting out a brake 3 14 

" " car 3 15 

" " " governor 2 4 

Cylinder head for high-speed ten- 
der brake 4 26 

D. 

D-5 brake valve 1 54 

D-8 brake valve 1 47 

" defects - 2 37 

Defective brakes, Locating 3 16 

" diaphragm in F-6 valve 2 45 
gasket between triple 

and auxiliary 2 31 

" graduating spring 2 26 

release spring ...-.- 2 32 

" rings in triple 2 30 

triple, Locating 2 28 

3 31 

Defects and remedies in air-brake 

system 2 1 
" signaling 

system 4 11 

of plain triple 2 29 

" quick-action triple 2 23 

Diaphragm of F-6 valve defective 2 45 
Direct-application-and-exhaust 

port 1 49 

Direct-application-and-supply port 1 49 

Discharge pipe stopped up 2 11 

" valves 1 19 

Double-heading 3 34 

Down grades, Descending long 4 35 



Sec. Page. 

Down grades, Handling trains on 3 30 

Drain cups 1 7 

Drip pipe of governor stoppea up 2 3 

Driver brake, Cam 3 42 

" " fails to apply 3 7 

" " " release 3 7 

" " " stay on 3 7 

Outside equalized .... 3 42 

Testing 3 6 

Duplex air gauge 1 10 

" feed- valve attachment 4 20 

pump-governor 4 20 

4 25 

Duties of the triple valve 1 31 

E. 

E-6 brake valve 1 54 

Effects of slack 3 2 

" " train-pipe length 3 3 

" unequal piston travel 3 3 

" " uneven distribution of 

loaded cars 3 3 

Efficiency of pump 2 4 

Eight-inch pump blowing 2 15 

" stopping 2 17 

Emergency application 1 33 

exhaust port 1 59 

part of triple 1 38 

position of D-8 valve 1 54 

" F-6 valve 1 59 
" Service stops 

from 2 49 

stops 3 25 

" Accidental 3 26 

valve 1 36 

" - " leaking 2 24 

Engineer's brake valve 1 5 

" Care of 2 46 

" The D-8 1 47 

" The F-6, D-5, 

or E-6 1 54 

warning port 1 57 

Equalization tests 3 35 

Equalized driver brake, Outside 3 42 

Equalizing piston 1 50 

port 1 ' 49 

reservoir 1 49 

" Importance of 2 48 

leaking 2 48 

Excess pressure, Failure to main- 
tain 2 38 

High 2 40 

spring, Testing 2 37 

valve faults 2 39 

Excessive pressure in pump, Effect 

of 2 8 



INDEX. 



Sec. Page. 

Exhaust of plain triple blowing 2 29 

Expander ring of brake piston 2 33 



F. 

F-6 brake valve 1 

" Leaks and defects in 2 

Operation of 1 

Feed groove, Size of. 2 

" valve attachment 1 

" " Cleaning 2 

Duplex 4 

Testing 2 

case gasket leaking 2 

pipe bracket 4 

" " piston sticking 2 

First reduction 3 

Force exerted in brake cylinder 3 

Freight equipment, Leaks and de- 
fects in 2 

trains, All-air 3 

Part-air 3 

Frozen couplings 3 

triple 2 

Fulcrum 3 

" Pressure on 3 

G. 

Gasket between triple and auxiliary 

defective 2 

Governor, Cutting out 1 

defects (improved) 2 

(old style) 2 

Duplex 4 

2 
2 
1 
2 
1 
2 
2 



Hose and couplings, Leaks in . 

" bursting 

couplings 

Locating a burst 



Sec. Page. 
3 13 
3 28 
1 43 
3 29 



piston stuck 

Graduating pin broken 

" port 

spring defective 

valve 

Importance of . 

" leaking 

Groove in rotary seat 2 

Gumming up of pump 2 

H. 

Hand-brakes, Use of 3 

HarTdling trains 3 

" " on down grades... 3 

Heating of pump 2 

High excess pressure 2 

" speed brake 4 

Operating 4 

" triple valve 4 

" of pump, Effect of 2 

Historical account of air brake 1 

Hodge system of brake gear 3 

Holding the brakes on 3 



I. 



Improved governor, Remedying de- 
fects in 2 1 

L. 

Lap position of D-8 valve 1 53 

" F-6 valve 1 59 

Law of compound lever 3 51 

Leakage from air cylinder 2 10 

groove 1 42 

" stopped up 2 32 

Leaks in auxiliary, Effect of 2 22 

" " branch pipes 3 13 

" freight equipment 2 31 

■' hose and couplings 3 13 

" plain triple 2 29 

" quick-action triple 2 23 

" " train pipe 3 12 

" " " Effect of 2 22 

Leaky air valves in pump 2 10 

" emergency valve 2 24 

equalizing reservoir 2 48 

feed-valve case gasket 2 45 

gasket in brake valve 2 44 

graduating valve 2 26 

pin valve in governor 2 1 

pipe in auxiliary 2 31 

piston rings in pump 2 9 

pump gasket 2 15 

release valve 2 31 

" reversing valve 2 14 

rotary valve 2 43 

" Testing for 2 38 

slide valve in pump 2 15 

" " triple 2 23 

steam valve of governor 2 2 

supply valve 2 44 

" train -pipe exhaust valve 2 46 

Leather of brake piston 2 32 

Length of train pipe 3 3 

Levers and leverage 3 44 

" Bent 3 49 

Compound 3 50 

" Simple 3 44 

" Straight 3 44 

The three classes of 3 47 

Life of pump 2 4 

Lift of air valves 2 7 

"Little drum" 1 49 

Locating defective brakes 3 16 



INDEX. 



Sec. Page. 

Locating defective triple 2 28 

" 3 31 

Location of main reservoir 1 9 

M. 

Main reservoir 1 8 

Effect of too small 2 12 

Locationof 1 9 

Size of 1 8 

" valve (8-inch pump) 1 17 

" " bushing (9Hnch pump) 1 22 
" " rings blowing (8-inch 

pump) 2 16 
(9|-mch 

pump) 2 15 

defective 2 19 

Make-up of train 3 1 

Measuring the piston travel 3 39 



Nine and a half inch pump blowing 
" " " " " " stopping 

Number of applications .. 

" reductions 

O. 

Oiling the brake cylinder 

" " pump 

" " triples 

Old-style governor, Defects in 

Operating the brake 

" " high-speed brake 

" " Sweeney compressor 

" " water brake 

Operation of 8-inch pump 

" " 9Hnch pump 

" D-8 valve 

" F-6 valve 

" pump governor 

" reducing valve(brake) 
" reducing valve (signal) 

Outside equalized driver brake 

Overcharging train pipe 

Overheating of pump 

P. 

Packing the pump 

Part-air freight train 

" " trains 

Picking up cars 

Pipe in auxiliary leaking 

Piston travel 

" " Adjustment of 

Long 

" " Measuring 

" " Proper amount of 

Short 



35 



Sec, Page. 

Piston travel, Unequal 3 3 

Plain triple valve 1 27 

" Action of 1 29 

" Description of 1 28 

" " leaks and defects 2 29 
Position of brake valve while run- 
ning 3 26 

Pounding in pump 2 12 

Preliminary-exhaust port 1 49 

" plug 2 46 

Pressure in brake cylinder 3 36 

" on brake shoe 3 58 

Pump, Cleaning out 2 6 

" Clearance in 2 13 

" Efficiency of 2 4 

" governor 1 4 

" Improved 1 13 

Old-style 2 3 

Testing 2 43 

3 5 

" Gumming up of 2 6 

" Heatingof 2 8 

" Lifeof 2 4 

" Oiling 2 5 

Packing 2 4 

Pounding in 2 12 

rundry 2 19 

Running 2 6 

Starting 2 6 

Temperature of 2 8 

Q. 

Quick action during service reduc- 
tion 3 31 

" part of triple 1 36 

triple 1 34 

" leaks and defects 2 23 

R. 

Receiving valves (of pump) 1 19 

Recharging a short train 2 42 

Reducing valve (high-speed brake) 4 21 

" " (signal) 4 4 

Reduction, First . . . ' 3 18 

Reductions, Number of 3 19 

Release position of D-8 valve 1 *51 

" F-6 valve 1 57 

" spring defective 2 32 

" valves leaking ; 2 31 

Releasing the brakes 1 33 

Relief port of governor stopped up 2 2 
"Removed corner" of triple slide 

valve 1 36 

Retaining valve 1 45 

" Duty of 2 34 

" Gain effected by.. 2 35 



INDEX. 



Sec. Page. 

Retaining valve leaks and defects 2 36 

Operation of 1 46 

Testing 2 34 

" Use of, on grades 2 34 

Reversing piston 1 17 

' ' rings blowing 2 16 

" defective 2 19 

" striking 2 13 

plate defective 2 19 

'• rod defective 2 19 

" worn 2 14 

the engine 3 26 

valve (8-inch pump) 1 17 

" leaks 2 16 

(9Hnch pump) .... 1 24 

" " " leaks 2 14 

Rotary seat 1 48 

valve 1 48 

hard to turn 2 40 

" leaking 2 43 

Rubber-seated valve 1 36 

Running position of D-8 valve 1 52 

" " " 3 26 

" F-6valve 1 58 

' 3 26 

test 3 15 

the pump 2 6 

travel 3 38 

S. 

Safety valve for high-speed brake 4 24 

Sand, Use of 3 32 

Service part of quick-action triple 1 36 

port of triple 1 30 

" position of D-8 valve 1 53 

" F-6 valve 1 59 

stops 3 17 

" • from emergency posi- 
tion 2 49 

Setting out a car 3 27 

Signal discharge valve fails to ex- 
haust 4 12 

pipe fails to charge 4 12 

valve 4 9 

whistle 4 4 

fails to blow 4 12 

Signaling 4 11 

Simplelever 3 44 

Slack adjuster 3 39 

" Effectsof 3 2 

Slide valve of pump leaking 2 15 

" " triple leaking 2 23 

Sliding of wheels 3 33 

Special apparatus for working 

heavy trains on grades 4 32 

Speed of pump 2 7 



Sec. 

Starting the pump 2 

Station stop 3 

Steam cylinder of 8-inch pump. 1 

" " 9Hnch pump 1 

Oiling 2 

piston rings blowing (8-inch) 2 

" (9|-mch) 2 

Stevens system of brake gear 3 

Sticky triple 2 

Stop-pin (in centerpiece) 2 

" " " Defective 2 

Stops, Emergency 3 

on grades 3 

Service 3 

Station 3 

Stopped-up strainers 2 

Stopping at water tanks and coal 

chutes 3 

by means of tail hose 3 

" of 8-inch pump 2 

" 9Hnch pump 2 

Straight lever 3 

" Straight-air " brake 1 

Strainers stopped up 2 

Supply valve leaking 2 

Sweeney air compressor 4 

T. 

Tail hose, Using, to make a stop 3 

Temperature of pump. 2 

" test of wheels 3 

Tender brake, Testing 3 

Terminal test of signal apparatus 4 

" " " train 3 

Test, Running 3 

" Temperature 3 

Testing device for signaling system 4 
for leaky gasket in brake 

valve 2 

rotary 2 

" triple- valve leaks 3 

" '• worn piston-rings 

(pump) 2 

the air pump 3 

" air-signal apparatus 4 

" brake valve 3 

" driver brake 3 

" excess-pressure spring 2 

" feed-valve attachment 2 

" pump governor 2 

3 

" tender brake 3 

" train at terminals 3 

" triple piston 3 

" valve 3 

Tests, Brake 4 



Page. 

6 
20 
16 
22 

5 
16 
15 
54 
27 
13 
18 
25 
20 
17 
20 
25 

23 
22 
17 
16 
44 
1 

25 
44 
41 



INDEX. 



Sec. Page. 



Time required to charge auxil- 
iaries 

Train, Make-up of 

Pipe 

check-valve 

couplings 

exhaust valve leaking 

governor 

leaks 

" Effect of 

Length of 

Overcharging 

Trains, Handling of 

Travel, Running 

Triple valve 

Care of 

Cleaning 

Duties of 

exhaust blowing 

frozen up 



High-speed brake 

leaks and defects 

" Testing for.. 



Sec. 
3 
3 
2 
2 
1 



Triple valve, Locating a defective 

" " piston, Testing 

" rings defective 

1 Plain 

Quick-action 

" Testing 3 

IT. 

Unequal piston travel 3 

Uneven distribution of loaded cars 3 

Use of hand-brakes ... 3 

V. 

Valve, Signal 4 

Valves of air pump, Lift of 2 



W 



Warning port (in engineer's valve) 1 

Water brake 4 

" tank stops 3 

Wheels sliding 3 

Whistle, Signal 4 

Worn reversing rod 2 



Page. 
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12 

30 
29 
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